Merge pull request #11450 from Snuffleupagus/eslint-web-prefer-const

Enable the ESLint `prefer-const` rule in the `web/` directory
2019-12-27 12:12:51 +01:00 · 2019-12-27 12:12:51 +01:00 · 47ab4b839f
commit 47ab4b839f
parent 9c767e3875 d9a5d50664
36 changed files with 377 additions and 378 deletions
--- a/web/.eslintrc
+++ b/web/.eslintrc
@ -9,5 +9,6 @@
    // ECMAScript 6
    "no-var": "error",
    "prefer-const": "error",
  },
 }
--- a/web/annotation_layer_builder.js
+++ b/web/annotation_layer_builder.js
@ -64,7 +64,7 @@ class AnnotationLayerBuilder {
        return;
      }
-      let parameters = {
+      const parameters = {
        viewport: viewport.clone({ dontFlip: true }),
        div: this.div,
        annotations,
--- a/web/app.js
+++ b/web/app.js
@ -108,7 +108,7 @@ const DefaultExternalServices = {
  },
 };
-let PDFViewerApplication = {
+const PDFViewerApplication = {
  initialBookmark: document.location.hash.substring(1),
  initialized: false,
  fellback: false,
@ -190,7 +190,7 @@ let PDFViewerApplication = {
    this.bindWindowEvents();
    // We can start UI localization now.
-    let appContainer = appConfig.appContainer || document.documentElement;
+    const appContainer = appConfig.appContainer || document.documentElement;
    this.l10n.translate(appContainer).then(() => {
      // Dispatch the 'localized' event on the `eventBus` once the viewer
      // has been fully initialized and translated.
@ -233,8 +233,8 @@ let PDFViewerApplication = {
    const waitOn = [];
    // Special debugging flags in the hash section of the URL.
-    let hash = document.location.hash.substring(1);
+    const hash = document.location.hash.substring(1);
-    let hashParams = parseQueryString(hash);
+    const hashParams = parseQueryString(hash);
    if (
      "disableworker" in hashParams &&
@ -280,14 +280,14 @@ let PDFViewerApplication = {
        case "visible":
        case "shadow":
        case "hover":
-          let viewer = this.appConfig.viewerContainer;
+          const viewer = this.appConfig.viewerContainer;
          viewer.classList.add("textLayer-" + hashParams["textlayer"]);
          break;
      }
    }
    if ("pdfbug" in hashParams) {
      AppOptions.set("pdfBug", true);
-      let enabled = hashParams["pdfbug"].split(",");
+      const enabled = hashParams["pdfbug"].split(",");
      waitOn.push(loadAndEnablePDFBug(enabled));
    }
    // It is not possible to change locale for the (various) extension builds.
@ -328,18 +328,18 @@ let PDFViewerApplication = {
      getGlobalEventBus(AppOptions.get("eventBusDispatchToDOM"));
    this.eventBus = eventBus;
-    let pdfRenderingQueue = new PDFRenderingQueue();
+    const pdfRenderingQueue = new PDFRenderingQueue();
    pdfRenderingQueue.onIdle = this.cleanup.bind(this);
    this.pdfRenderingQueue = pdfRenderingQueue;
-    let pdfLinkService = new PDFLinkService({
+    const pdfLinkService = new PDFLinkService({
      eventBus,
      externalLinkTarget: AppOptions.get("externalLinkTarget"),
      externalLinkRel: AppOptions.get("externalLinkRel"),
    });
    this.pdfLinkService = pdfLinkService;
-    let downloadManager = this.externalServices.createDownloadManager({
+    const downloadManager = this.externalServices.createDownloadManager({
      disableCreateObjectURL: AppOptions.get("disableCreateObjectURL"),
    });
    this.downloadManager = downloadManager;
@ -519,7 +519,7 @@ let PDFViewerApplication = {
        document.fullscreenEnabled === true ||
        document.mozFullScreenEnabled === true;
    } else {
-      let doc = document.documentElement;
+      const doc = document.documentElement;
      support = !!(
        doc.requestFullscreen ||
        doc.mozRequestFullScreen ||
@ -552,7 +552,7 @@ let PDFViewerApplication = {
  },
  get loadingBar() {
-    let bar = new ProgressBar("#loadingBar");
+    const bar = new ProgressBar("#loadingBar");
    return shadow(this, "loadingBar", bar);
  },
@ -632,14 +632,14 @@ let PDFViewerApplication = {
   *                      destruction is completed.
   */
  async close() {
-    let errorWrapper = this.appConfig.errorWrapper.container;
+    const errorWrapper = this.appConfig.errorWrapper.container;
    errorWrapper.setAttribute("hidden", "true");
    if (!this.pdfLoadingTask) {
      return undefined;
    }
-    let promise = this.pdfLoadingTask.destroy();
+    const promise = this.pdfLoadingTask.destroy();
    this.pdfLoadingTask = null;
    if (this.pdfDocument) {
@ -692,11 +692,11 @@ let PDFViewerApplication = {
    }
    // Set the necessary global worker parameters, using the available options.
    const workerParameters = AppOptions.getAll(OptionKind.WORKER);
-    for (let key in workerParameters) {
+    for (const key in workerParameters) {
      GlobalWorkerOptions[key] = workerParameters[key];
    }
-    let parameters = Object.create(null);
+    const parameters = Object.create(null);
    if (typeof file === "string") {
      // URL
      this.setTitleUsingUrl(file);
@ -710,7 +710,7 @@ let PDFViewerApplication = {
    }
    // Set the necessary API parameters, using the available options.
    const apiParameters = AppOptions.getAll(OptionKind.API);
-    for (let key in apiParameters) {
+    for (const key in apiParameters) {
      let value = apiParameters[key];
      if (key === "docBaseUrl" && !value) {
@ -727,7 +727,7 @@ let PDFViewerApplication = {
    }
    if (args) {
-      for (let key in args) {
+      for (const key in args) {
        const value = args[key];
        if (key === "length") {
@ -737,7 +737,7 @@ let PDFViewerApplication = {
      }
    }
-    let loadingTask = getDocument(parameters);
+    const loadingTask = getDocument(parameters);
    this.pdfLoadingTask = loadingTask;
    loadingTask.onPassword = (updateCallback, reason) => {
@ -762,7 +762,7 @@ let PDFViewerApplication = {
          return undefined; // Ignore errors for previously opened PDF files.
        }
-        let message = exception && exception.message;
+        const message = exception && exception.message;
        let loadingErrorMessage;
        if (exception instanceof InvalidPDFException) {
          // change error message also for other builds
@ -805,12 +805,12 @@ let PDFViewerApplication = {
      downloadManager.downloadUrl(url, filename);
    }
-    let url = this.baseUrl;
+    const url = this.baseUrl;
    // Use this.url instead of this.baseUrl to perform filename detection based
    // on the reference fragment as ultimate fallback if needed.
-    let filename =
+    const filename =
      this.contentDispositionFilename || getPDFFileNameFromURL(this.url);
-    let downloadManager = this.downloadManager;
+    const downloadManager = this.downloadManager;
    downloadManager.onerror = err => {
      // This error won't really be helpful because it's likely the
      // fallback won't work either (or is already open).
@ -867,7 +867,7 @@ let PDFViewerApplication = {
   *                              optionally a 'stack' property.
   */
  error(message, moreInfo) {
-    let moreInfoText = [
+    const moreInfoText = [
      this.l10n.get(
        "error_version_info",
        { version: version || "?", build: build || "?" },
@ -916,21 +916,21 @@ let PDFViewerApplication = {
      typeof PDFJSDev === "undefined" ||
      !PDFJSDev.test("FIREFOX || MOZCENTRAL")
    ) {
-      let errorWrapperConfig = this.appConfig.errorWrapper;
+      const errorWrapperConfig = this.appConfig.errorWrapper;
-      let errorWrapper = errorWrapperConfig.container;
+      const errorWrapper = errorWrapperConfig.container;
      errorWrapper.removeAttribute("hidden");
-      let errorMessage = errorWrapperConfig.errorMessage;
+      const errorMessage = errorWrapperConfig.errorMessage;
      errorMessage.textContent = message;
-      let closeButton = errorWrapperConfig.closeButton;
+      const closeButton = errorWrapperConfig.closeButton;
      closeButton.onclick = function() {
        errorWrapper.setAttribute("hidden", "true");
      };
-      let errorMoreInfo = errorWrapperConfig.errorMoreInfo;
+      const errorMoreInfo = errorWrapperConfig.errorMoreInfo;
-      let moreInfoButton = errorWrapperConfig.moreInfoButton;
+      const moreInfoButton = errorWrapperConfig.moreInfoButton;
-      let lessInfoButton = errorWrapperConfig.lessInfoButton;
+      const lessInfoButton = errorWrapperConfig.lessInfoButton;
      moreInfoButton.onclick = function() {
        errorMoreInfo.removeAttribute("hidden");
        moreInfoButton.setAttribute("hidden", "true");
@ -964,7 +964,7 @@ let PDFViewerApplication = {
      // already been fetched (only an issue when disableAutoFetch is enabled).
      return;
    }
-    let percent = Math.round(level * 100);
+    const percent = Math.round(level * 100);
    // When we transition from full request to range requests, it's possible
    // that we discard some of the loaded data. This can cause the loading
    // bar to move backwards. So prevent this by only updating the bar if it
@ -1038,13 +1038,13 @@ let PDFViewerApplication = {
    this.pdfLinkService.setDocument(pdfDocument, baseDocumentUrl);
    this.pdfDocumentProperties.setDocument(pdfDocument, this.url);
-    let pdfViewer = this.pdfViewer;
+    const pdfViewer = this.pdfViewer;
    pdfViewer.setDocument(pdfDocument);
-    let firstPagePromise = pdfViewer.firstPagePromise;
+    const firstPagePromise = pdfViewer.firstPagePromise;
-    let pagesPromise = pdfViewer.pagesPromise;
+    const pagesPromise = pdfViewer.pagesPromise;
-    let onePageRendered = pdfViewer.onePageRendered;
+    const onePageRendered = pdfViewer.onePageRendered;
-    let pdfThumbnailViewer = this.pdfThumbnailViewer;
+    const pdfThumbnailViewer = this.pdfThumbnailViewer;
    pdfThumbnailViewer.setDocument(pdfDocument);
    firstPagePromise.then(pdfPage => {
@ -1182,8 +1182,7 @@ let PDFViewerApplication = {
      if (!labels || AppOptions.get("disablePageLabels")) {
        return;
      }
-      let i = 0,
+      const numLabels = labels.length;
        numLabels = labels.length;
      if (numLabels !== this.pagesCount) {
        console.error(
          "The number of Page Labels does not match " +
@ -1191,6 +1190,7 @@ let PDFViewerApplication = {
        );
        return;
      }
      let i = 0;
      // Ignore page labels that correspond to standard page numbering.
      while (i < numLabels && labels[i] === (i + 1).toString()) {
        i++;
@ -1354,7 +1354,7 @@ let PDFViewerApplication = {
              }.bind(null, info.Producer.toLowerCase())
            );
          }
-          let formType = !info.IsAcroFormPresent
+          const formType = !info.IsAcroFormPresent
            ? null
            : info.IsXFAPresent
            ? "xfa"
@ -1507,9 +1507,9 @@ let PDFViewerApplication = {
      return;
    }
-    let pagesOverview = this.pdfViewer.getPagesOverview();
+    const pagesOverview = this.pdfViewer.getPagesOverview();
-    let printContainer = this.appConfig.printContainer;
+    const printContainer = this.appConfig.printContainer;
-    let printService = PDFPrintServiceFactory.instance.createPrintService(
+    const printService = PDFPrintServiceFactory.instance.createPrintService(
      this.pdfDocument,
      pagesOverview,
      printContainer,
@ -1542,7 +1542,7 @@ let PDFViewerApplication = {
    if (!this.pdfDocument) {
      return;
    }
-    let newRotation = (this.pdfViewer.pagesRotation + 360 + delta) % 360;
+    const newRotation = (this.pdfViewer.pagesRotation + 360 + delta) % 360;
    this.pdfViewer.pagesRotation = newRotation;
    // Note that the thumbnail viewer is updated, and rendering is triggered,
    // in the 'rotationchanging' event handler.
@ -1556,7 +1556,7 @@ let PDFViewerApplication = {
  },
  bindEvents() {
-    let { eventBus, _boundEvents } = this;
+    const { eventBus, _boundEvents } = this;
    _boundEvents.beforePrint = this.beforePrint.bind(this);
    _boundEvents.afterPrint = this.afterPrint.bind(this);
@ -1605,7 +1605,7 @@ let PDFViewerApplication = {
  },
  bindWindowEvents() {
-    let { eventBus, _boundEvents } = this;
+    const { eventBus, _boundEvents } = this;
    _boundEvents.windowResize = () => {
      eventBus.dispatch("resize", { source: window });
@ -1634,7 +1634,7 @@ let PDFViewerApplication = {
  },
  unbindEvents() {
-    let { eventBus, _boundEvents } = this;
+    const { eventBus, _boundEvents } = this;
    eventBus.off("resize", webViewerResize);
    eventBus.off("hashchange", webViewerHashchange);
@ -1683,7 +1683,7 @@ let PDFViewerApplication = {
  },
  unbindWindowEvents() {
-    let { _boundEvents } = this;
+    const { _boundEvents } = this;
    window.removeEventListener("visibilitychange", webViewerVisibilityChange);
    window.removeEventListener("wheel", webViewerWheel);
@ -1713,12 +1713,12 @@ if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
      return;
    }
    try {
-      let viewerOrigin = new URL(window.location.href).origin || "null";
+      const viewerOrigin = new URL(window.location.href).origin || "null";
      if (HOSTED_VIEWER_ORIGINS.includes(viewerOrigin)) {
        // Hosted or local viewer, allow for any file locations
        return;
      }
-      let { origin, protocol } = new URL(file, window.location.href);
+      const { origin, protocol } = new URL(file, window.location.href);
      // Removing of the following line will not guarantee that the viewer will
      // start accepting URLs from foreign origin -- CORS headers on the remote
      // server must be properly configured.
@ -1729,7 +1729,7 @@ if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
        throw new Error("file origin does not match viewer's");
      }
    } catch (ex) {
-      let message = ex && ex.message;
+      const message = ex && ex.message;
      PDFViewerApplication.l10n
        .get("loading_error", null, "An error occurred while loading the PDF.")
        .then(loadingErrorMessage => {
@ -1755,7 +1755,7 @@ async function loadFakeWorker() {
 }
 function loadAndEnablePDFBug(enabledTabs) {
-  let appConfig = PDFViewerApplication.appConfig;
+  const appConfig = PDFViewerApplication.appConfig;
  return loadScript(appConfig.debuggerScriptPath).then(function() {
    PDFBug.enable(enabledTabs);
    PDFBug.init(
@ -1769,11 +1769,11 @@ function loadAndEnablePDFBug(enabledTabs) {
 }
 function webViewerInitialized() {
-  let appConfig = PDFViewerApplication.appConfig;
+  const appConfig = PDFViewerApplication.appConfig;
  let file;
  if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
-    let queryString = document.location.search.substring(1);
+    const queryString = document.location.search.substring(1);
-    let params = parseQueryString(queryString);
+    const params = parseQueryString(queryString);
    file = "file" in params ? params.file : AppOptions.get("defaultUrl");
    validateFileURL(file);
  } else if (PDFJSDev.test("FIREFOX || MOZCENTRAL")) {
@ -1783,7 +1783,7 @@ function webViewerInitialized() {
  }
  if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
-    let fileInput = document.createElement("input");
+    const fileInput = document.createElement("input");
    fileInput.id = appConfig.openFileInputName;
    fileInput.className = "fileInput";
    fileInput.setAttribute("type", "file");
@ -1803,7 +1803,7 @@ function webViewerInitialized() {
    }
    fileInput.addEventListener("change", function(evt) {
-      let files = evt.target.files;
+      const files = evt.target.files;
      if (!files || files.length === 0) {
        return;
      }
@ -1924,9 +1924,9 @@ if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
 }
 function webViewerPageRendered(evt) {
-  let pageNumber = evt.pageNumber;
+  const pageNumber = evt.pageNumber;
-  let pageIndex = pageNumber - 1;
+  const pageIndex = pageNumber - 1;
-  let pageView = PDFViewerApplication.pdfViewer.getPageView(pageIndex);
+  const pageView = PDFViewerApplication.pdfViewer.getPageView(pageIndex);
  // If the page is still visible when it has finished rendering,
  // ensure that the page number input loading indicator is hidden.
@ -1942,7 +1942,7 @@ function webViewerPageRendered(evt) {
  // Use the rendered page to set the corresponding thumbnail image.
  if (PDFViewerApplication.pdfSidebar.isThumbnailViewVisible) {
-    let thumbnailView = PDFViewerApplication.pdfThumbnailViewer.getThumbnail(
+    const thumbnailView = PDFViewerApplication.pdfThumbnailViewer.getThumbnail(
      pageIndex
    );
    thumbnailView.setImage(pageView);
@ -2004,10 +2004,9 @@ function webViewerTextLayerRendered(evt) {
  }
 }
-function webViewerPageMode(evt) {
+function webViewerPageMode({ mode }) {
  // Handle the 'pagemode' hash parameter, see also `PDFLinkService_setHash`.
-  let mode = evt.mode,
+  let view;
    view;
  switch (mode) {
    case "thumbs":
      view = SidebarView.THUMBS;
@ -2032,7 +2031,7 @@ function webViewerPageMode(evt) {
 function webViewerNamedAction(evt) {
  // Processing couple of named actions that might be useful.
  // See also PDFLinkService.executeNamedAction
-  let action = evt.action;
+  const action = evt.action;
  switch (action) {
    case "GoToPage":
      PDFViewerApplication.appConfig.toolbar.pageNumber.select();
@ -2047,7 +2046,7 @@ function webViewerNamedAction(evt) {
 }
 function webViewerPresentationModeChanged(evt) {
-  let { active, switchInProgress } = evt;
+  const { active, switchInProgress } = evt;
  PDFViewerApplication.pdfViewer.presentationModeState = switchInProgress
    ? PresentationModeState.CHANGING
    : active
@ -2059,7 +2058,7 @@ function webViewerSidebarViewChanged(evt) {
  PDFViewerApplication.pdfRenderingQueue.isThumbnailViewEnabled =
    PDFViewerApplication.pdfSidebar.isThumbnailViewVisible;
-  let store = PDFViewerApplication.store;
+  const store = PDFViewerApplication.store;
  if (store && PDFViewerApplication.isInitialViewSet) {
    // Only update the storage when the document has been loaded *and* rendered.
    store.set("sidebarView", evt.view).catch(function() {});
@ -2067,7 +2066,7 @@ function webViewerSidebarViewChanged(evt) {
 }
 function webViewerUpdateViewarea(evt) {
-  let location = evt.location,
+  const location = evt.location,
    store = PDFViewerApplication.store;
  if (store && PDFViewerApplication.isInitialViewSet) {
@ -2083,22 +2082,22 @@ function webViewerUpdateViewarea(evt) {
        /* unable to write to storage */
      });
  }
-  let href = PDFViewerApplication.pdfLinkService.getAnchorUrl(
+  const href = PDFViewerApplication.pdfLinkService.getAnchorUrl(
    location.pdfOpenParams
  );
  PDFViewerApplication.appConfig.toolbar.viewBookmark.href = href;
  PDFViewerApplication.appConfig.secondaryToolbar.viewBookmarkButton.href = href;
  // Show/hide the loading indicator in the page number input element.
-  let currentPage = PDFViewerApplication.pdfViewer.getPageView(
+  const currentPage = PDFViewerApplication.pdfViewer.getPageView(
    PDFViewerApplication.page - 1
  );
-  let loading = currentPage.renderingState !== RenderingStates.FINISHED;
+  const loading = currentPage.renderingState !== RenderingStates.FINISHED;
  PDFViewerApplication.toolbar.updateLoadingIndicatorState(loading);
 }
 function webViewerScrollModeChanged(evt) {
-  let store = PDFViewerApplication.store;
+  const store = PDFViewerApplication.store;
  if (store && PDFViewerApplication.isInitialViewSet) {
    // Only update the storage when the document has been loaded *and* rendered.
    store.set("scrollMode", evt.mode).catch(function() {});
@ -2106,7 +2105,7 @@ function webViewerScrollModeChanged(evt) {
 }
 function webViewerSpreadModeChanged(evt) {
-  let store = PDFViewerApplication.store;
+  const store = PDFViewerApplication.store;
  if (store && PDFViewerApplication.isInitialViewSet) {
    // Only update the storage when the document has been loaded *and* rendered.
    store.set("spreadMode", evt.mode).catch(function() {});
@ -2114,11 +2113,11 @@ function webViewerSpreadModeChanged(evt) {
 }
 function webViewerResize() {
-  let { pdfDocument, pdfViewer } = PDFViewerApplication;
+  const { pdfDocument, pdfViewer } = PDFViewerApplication;
  if (!pdfDocument) {
    return;
  }
-  let currentScaleValue = pdfViewer.currentScaleValue;
+  const currentScaleValue = pdfViewer.currentScaleValue;
  if (
    currentScaleValue === "auto" ||
    currentScaleValue === "page-fit" ||
@ -2131,7 +2130,7 @@ function webViewerResize() {
 }
 function webViewerHashchange(evt) {
-  let hash = evt.hash;
+  const hash = evt.hash;
  if (!hash) {
    return;
  }
@ -2151,7 +2150,7 @@ if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
    ) {
      return; // Opening a new PDF file isn't supported in Presentation Mode.
    }
-    let file = evt.fileInput.files[0];
+    const file = evt.fileInput.files[0];
    if (URL.createObjectURL && !AppOptions.get("disableCreateObjectURL")) {
      let url = URL.createObjectURL(file);
@ -2162,16 +2161,16 @@ if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
    } else {
      PDFViewerApplication.setTitleUsingUrl(file.name);
      // Read the local file into a Uint8Array.
-      let fileReader = new FileReader();
+      const fileReader = new FileReader();
      fileReader.onload = function webViewerChangeFileReaderOnload(evt) {
-        let buffer = evt.target.result;
+        const buffer = evt.target.result;
        PDFViewerApplication.open(new Uint8Array(buffer));
      };
      fileReader.readAsArrayBuffer(file);
    }
    // URL does not reflect proper document location - hiding some icons.
-    let appConfig = PDFViewerApplication.appConfig;
+    const appConfig = PDFViewerApplication.appConfig;
    appConfig.toolbar.viewBookmark.setAttribute("hidden", "true");
    appConfig.secondaryToolbar.viewBookmarkButton.setAttribute(
      "hidden",
@ -2187,7 +2186,7 @@ function webViewerPresentationMode() {
 }
 function webViewerOpenFile() {
  if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
-    let openFileInputName = PDFViewerApplication.appConfig.openFileInputName;
+    const openFileInputName = PDFViewerApplication.appConfig.openFileInputName;
    document.getElementById(openFileInputName).click();
  }
 }
@ -2223,7 +2222,7 @@ function webViewerZoomReset() {
  PDFViewerApplication.zoomReset();
 }
 function webViewerPageNumberChanged(evt) {
-  let pdfViewer = PDFViewerApplication.pdfViewer;
+  const pdfViewer = PDFViewerApplication.pdfViewer;
  // Note that for `<input type="number">` HTML elements, an empty string will
  // be returned for non-number inputs; hence we simply do nothing in that case.
  if (evt.value !== "") {
@ -2318,7 +2317,7 @@ function webViewerRotationChanging(evt) {
 }
 function webViewerPageChanging(evt) {
-  let page = evt.pageNumber;
+  const page = evt.pageNumber;
  PDFViewerApplication.toolbar.setPageNumber(page, evt.pageLabel || null);
  PDFViewerApplication.secondaryToolbar.setPageNumber(page);
@ -2329,7 +2328,7 @@ function webViewerPageChanging(evt) {
  // We need to update stats.
  if (typeof Stats !== "undefined" && Stats.enabled) {
-    let pageView = PDFViewerApplication.pdfViewer.getPageView(page - 1);
+    const pageView = PDFViewerApplication.pdfViewer.getPageView(page - 1);
    if (pageView && pageView.stats) {
      Stats.add(page, pageView.stats);
    }
@ -2374,27 +2373,27 @@ function webViewerWheel(evt) {
      return;
    }
-    let previousScale = pdfViewer.currentScale;
+    const previousScale = pdfViewer.currentScale;
-    let delta = normalizeWheelEventDelta(evt);
+    const delta = normalizeWheelEventDelta(evt);
    const MOUSE_WHEEL_DELTA_PER_PAGE_SCALE = 3.0;
-    let ticks = delta * MOUSE_WHEEL_DELTA_PER_PAGE_SCALE;
+    const ticks = delta * MOUSE_WHEEL_DELTA_PER_PAGE_SCALE;
    if (ticks < 0) {
      PDFViewerApplication.zoomOut(-ticks);
    } else {
      PDFViewerApplication.zoomIn(ticks);
    }
-    let currentScale = pdfViewer.currentScale;
+    const currentScale = pdfViewer.currentScale;
    if (previousScale !== currentScale) {
      // After scaling the page via zoomIn/zoomOut, the position of the upper-
      // left corner is restored. When the mouse wheel is used, the position
      // under the cursor should be restored instead.
-      let scaleCorrectionFactor = currentScale / previousScale - 1;
+      const scaleCorrectionFactor = currentScale / previousScale - 1;
-      let rect = pdfViewer.container.getBoundingClientRect();
+      const rect = pdfViewer.container.getBoundingClientRect();
-      let dx = evt.clientX - rect.left;
+      const dx = evt.clientX - rect.left;
-      let dy = evt.clientY - rect.top;
+      const dy = evt.clientY - rect.top;
      pdfViewer.container.scrollLeft += dx * scaleCorrectionFactor;
      pdfViewer.container.scrollTop += dy * scaleCorrectionFactor;
    }
@ -2407,7 +2406,7 @@ function webViewerClick(evt) {
  if (!PDFViewerApplication.secondaryToolbar.isOpen) {
    return;
  }
-  let appConfig = PDFViewerApplication.appConfig;
+  const appConfig = PDFViewerApplication.appConfig;
  if (
    PDFViewerApplication.pdfViewer.containsElement(evt.target) ||
    (appConfig.toolbar.container.contains(evt.target) &&
@ -2424,14 +2423,15 @@ function webViewerKeyDown(evt) {
  let handled = false,
    ensureViewerFocused = false;
-  let cmd =
+  const cmd =
    (evt.ctrlKey ? 1 : 0) |
    (evt.altKey ? 2 : 0) |
    (evt.shiftKey ? 4 : 0) |
    (evt.metaKey ? 8 : 0);
-  let pdfViewer = PDFViewerApplication.pdfViewer;
+  const pdfViewer = PDFViewerApplication.pdfViewer;
-  let isViewerInPresentationMode = pdfViewer && pdfViewer.isInPresentationMode;
+  const isViewerInPresentationMode =
    pdfViewer && pdfViewer.isInPresentationMode;
  // First, handle the key bindings that are independent whether an input
  // control is selected or not.
@ -2446,7 +2446,7 @@ function webViewerKeyDown(evt) {
        break;
      case 71: // g
        if (!PDFViewerApplication.supportsIntegratedFind) {
-          let findState = PDFViewerApplication.findController.state;
+          const findState = PDFViewerApplication.findController.state;
          if (findState) {
            PDFViewerApplication.findController.executeCommand("findagain", {
              query: findState.query,
@ -2549,8 +2549,8 @@ function webViewerKeyDown(evt) {
  // Some shortcuts should not get handled if a control/input element
  // is selected.
-  let curElement = document.activeElement || document.querySelector(":focus");
+  const curElement = document.activeElement || document.querySelector(":focus");
-  let curElementTagName = curElement && curElement.tagName.toUpperCase();
+  const curElementTagName = curElement && curElement.tagName.toUpperCase();
  if (
    curElementTagName === "INPUT" ||
    curElementTagName === "TEXTAREA" ||
@ -2777,7 +2777,7 @@ function apiPageModeToSidebarView(mode) {
 }
 /* Abstract factory for the print service. */
-let PDFPrintServiceFactory = {
+const PDFPrintServiceFactory = {
  instance: {
    supportsPrinting: false,
    createPrintService() {
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@ -82,9 +82,9 @@ const DEFAULT_CACHE_SIZE = 10;
 */
 function PDFPageViewBuffer(size) {
-  let data = [];
+  const data = [];
  this.push = function(view) {
-    let i = data.indexOf(view);
+    const i = data.indexOf(view);
    if (i >= 0) {
      data.splice(i, 1);
    }
@ -279,7 +279,7 @@ class BaseViewer {
    }
    let page = val | 0; // Fallback page number.
    if (this._pageLabels) {
-      let i = this._pageLabels.indexOf(val);
+      const i = this._pageLabels.indexOf(val);
      if (i >= 0) {
        page = i + 1;
      }
@ -353,10 +353,10 @@ class BaseViewer {
    }
    this._pagesRotation = rotation;
-    let pageNumber = this._currentPageNumber;
+    const pageNumber = this._currentPageNumber;
    for (let i = 0, ii = this._pages.length; i < ii; i++) {
-      let pageView = this._pages[i];
+      const pageView = this._pages[i];
      pageView.update(pageView.scale, rotation);
    }
    // Prevent errors in case the rotation changes *before* the scale has been
@ -398,9 +398,9 @@ class BaseViewer {
    if (!pdfDocument) {
      return;
    }
-    let pagesCount = pdfDocument.numPages;
+    const pagesCount = pdfDocument.numPages;
-    let pagesCapability = createPromiseCapability();
+    const pagesCapability = createPromiseCapability();
    this.pagesPromise = pagesCapability.promise;
    pagesCapability.promise.then(() => {
@ -443,14 +443,14 @@ class BaseViewer {
    // viewport for all pages
    firstPagePromise
      .then(firstPdfPage => {
-        let scale = this.currentScale;
+        const scale = this.currentScale;
        const viewport = firstPdfPage.getViewport({ scale: scale * CSS_UNITS });
        for (let pageNum = 1; pageNum <= pagesCount; ++pageNum) {
          let textLayerFactory = null;
          if (this.textLayerMode !== TextLayerMode.DISABLE) {
            textLayerFactory = this;
          }
-          let pageView = new PDFPageView({
+          const pageView = new PDFPageView({
            container: this._setDocumentViewerElement,
            eventBus: this.eventBus,
            id: pageNum,
@ -509,7 +509,7 @@ class BaseViewer {
          for (let pageNum = 2; pageNum <= pagesCount; ++pageNum) {
            pdfDocument.getPage(pageNum).then(
              pdfPage => {
-                let pageView = this._pages[pageNum - 1];
+                const pageView = this._pages[pageNum - 1];
                if (!pageView.pdfPage) {
                  pageView.setPdfPage(pdfPage);
                }
@ -561,8 +561,8 @@ class BaseViewer {
    }
    // Update all the `PDFPageView` instances.
    for (let i = 0, ii = this._pages.length; i < ii; i++) {
-      let pageView = this._pages[i];
+      const pageView = this._pages[i];
-      let label = this._pageLabels && this._pageLabels[i];
+      const label = this._pageLabels && this._pageLabels[i];
      pageView.setPageLabel(label);
    }
  }
@ -665,7 +665,7 @@ class BaseViewer {
    if (scale > 0) {
      this._setScaleUpdatePages(scale, value, noScroll, /* preset = */ false);
    } else {
-      let currentPage = this._pages[this._currentPageNumber - 1];
+      const currentPage = this._pages[this._currentPageNumber - 1];
      if (!currentPage) {
        return;
      }
@ -676,10 +676,10 @@ class BaseViewer {
      if (!noPadding && this._isScrollModeHorizontal) {
        [hPadding, vPadding] = [vPadding, hPadding]; // Swap the padding values.
      }
-      let pageWidthScale =
+      const pageWidthScale =
        ((this.container.clientWidth - hPadding) / currentPage.width) *
        currentPage.scale;
-      let pageHeightScale =
+      const pageHeightScale =
        ((this.container.clientHeight - vPadding) / currentPage.height) *
        currentPage.scale;
      switch (value) {
@ -698,7 +698,7 @@ class BaseViewer {
        case "auto":
          // For pages in landscape mode, fit the page height to the viewer
          // *unless* the page would thus become too wide to fit horizontally.
-          let horizontalScale = isPortraitOrientation(currentPage)
+          const horizontalScale = isPortraitOrientation(currentPage)
            ? pageWidthScale
            : Math.min(pageHeightScale, pageWidthScale);
          scale = Math.min(MAX_AUTO_SCALE, horizontalScale);
@ -723,7 +723,7 @@ class BaseViewer {
      this._setScale(this._currentScaleValue, true);
    }
-    let pageView = this._pages[this._currentPageNumber - 1];
+    const pageView = this._pages[this._currentPageNumber - 1];
    this._scrollIntoView({ pageDiv: pageView.div });
  }
@ -768,12 +768,12 @@ class BaseViewer {
      height = 0,
      widthScale,
      heightScale;
-    let changeOrientation = pageView.rotation % 180 === 0 ? false : true;
+    const changeOrientation = pageView.rotation % 180 === 0 ? false : true;
-    let pageWidth =
+    const pageWidth =
      (changeOrientation ? pageView.height : pageView.width) /
      pageView.scale /
      CSS_UNITS;
-    let pageHeight =
+    const pageHeight =
      (changeOrientation ? pageView.width : pageView.height) /
      pageView.scale /
      CSS_UNITS;
@ -817,8 +817,8 @@ class BaseViewer {
        y = destArray[3];
        width = destArray[4] - x;
        height = destArray[5] - y;
-        let hPadding = this.removePageBorders ? 0 : SCROLLBAR_PADDING;
+        const hPadding = this.removePageBorders ? 0 : SCROLLBAR_PADDING;
-        let vPadding = this.removePageBorders ? 0 : VERTICAL_PADDING;
+        const vPadding = this.removePageBorders ? 0 : VERTICAL_PADDING;
        widthScale =
          (this.container.clientWidth - hPadding) / width / CSS_UNITS;
@ -848,7 +848,7 @@ class BaseViewer {
      return;
    }
-    let boundingRect = [
+    const boundingRect = [
      pageView.viewport.convertToViewportPoint(x, y),
      pageView.viewport.convertToViewportPoint(x + width, y + height),
    ];
@ -870,24 +870,24 @@ class BaseViewer {
  }
  _updateLocation(firstPage) {
-    let currentScale = this._currentScale;
+    const currentScale = this._currentScale;
-    let currentScaleValue = this._currentScaleValue;
+    const currentScaleValue = this._currentScaleValue;
-    let normalizedScaleValue =
+    const normalizedScaleValue =
      parseFloat(currentScaleValue) === currentScale
        ? Math.round(currentScale * 10000) / 100
        : currentScaleValue;
-    let pageNumber = firstPage.id;
+    const pageNumber = firstPage.id;
    let pdfOpenParams = "#page=" + pageNumber;
    pdfOpenParams += "&zoom=" + normalizedScaleValue;
-    let currentPageView = this._pages[pageNumber - 1];
+    const currentPageView = this._pages[pageNumber - 1];
-    let container = this.container;
+    const container = this.container;
-    let topLeft = currentPageView.getPagePoint(
+    const topLeft = currentPageView.getPagePoint(
      container.scrollLeft - firstPage.x,
      container.scrollTop - firstPage.y
    );
-    let intLeft = Math.round(topLeft[0]);
+    const intLeft = Math.round(topLeft[0]);
-    let intTop = Math.round(topLeft[1]);
+    const intTop = Math.round(topLeft[1]);
    pdfOpenParams += "," + intLeft + "," + intTop;
    this._location = {
@ -1066,11 +1066,11 @@ class BaseViewer {
  }
  forceRendering(currentlyVisiblePages) {
-    let visiblePages = currentlyVisiblePages || this._getVisiblePages();
+    const visiblePages = currentlyVisiblePages || this._getVisiblePages();
-    let scrollAhead = this._isScrollModeHorizontal
+    const scrollAhead = this._isScrollModeHorizontal
      ? this.scroll.right
      : this.scroll.down;
-    let pageView = this.renderingQueue.getHighestPriority(
+    const pageView = this.renderingQueue.getHighestPriority(
      visiblePages,
      this._pages,
      scrollAhead
@ -1140,9 +1140,9 @@ class BaseViewer {
   *   widths and heights.
   */
  get hasEqualPageSizes() {
-    let firstPageView = this._pages[0];
+    const firstPageView = this._pages[0];
    for (let i = 1, ii = this._pages.length; i < ii; ++i) {
-      let pageView = this._pages[i];
+      const pageView = this._pages[i];
      if (
        pageView.width !== firstPageView.width ||
        pageView.height !== firstPageView.height
@ -1158,8 +1158,8 @@ class BaseViewer {
   * @returns {Array} Array of objects with width/height/rotation fields.
   */
  getPagesOverview() {
-    let pagesOverview = this._pages.map(function(pageView) {
+    const pagesOverview = this._pages.map(function(pageView) {
-      let viewport = pageView.pdfPage.getViewport({ scale: 1 });
+      const viewport = pageView.pdfPage.getViewport({ scale: 1 });
      return {
        width: viewport.width,
        height: viewport.height,
@ -1169,7 +1169,7 @@ class BaseViewer {
    if (!this.enablePrintAutoRotate) {
      return pagesOverview;
    }
-    let isFirstPagePortrait = isPortraitOrientation(pagesOverview[0]);
+    const isFirstPagePortrait = isPortraitOrientation(pagesOverview[0]);
    return pagesOverview.map(function(size) {
      if (isFirstPagePortrait === isPortraitOrientation(size)) {
        return size;
--- a/web/chromecom.js
+++ b/web/chromecom.js
@ -26,7 +26,7 @@ if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("CHROME")) {
  );
 }
-let ChromeCom = {
+const ChromeCom = {
  /**
   * Creates an event that the extension is listening for and will
   * asynchronously respond by calling the callback.
@ -38,7 +38,7 @@ let ChromeCom = {
   *   immediately invoked with no arguments.
   */
  request(action, data, callback) {
-    let message = {
+    const message = {
      action,
      data,
    };
@ -110,7 +110,7 @@ let ChromeCom = {
 };
 function getEmbedderOrigin(callback) {
-  let origin = window === top ? location.origin : location.ancestorOrigins[0];
+  const origin = window === top ? location.origin : location.ancestorOrigins[0];
  if (origin === "null") {
    // file:-URLs, data-URLs, sandboxed frames, etc.
    getParentOrigin(callback);
@ -171,14 +171,14 @@ function requestAccessToLocalFile(fileUrl, overlayManager, callback) {
    );
  }
  chromeFileAccessOverlayPromise.then(function() {
-    let iconPath = chrome.runtime.getManifest().icons[48];
+    const iconPath = chrome.runtime.getManifest().icons[48];
    document.getElementById("chrome-pdfjs-logo-bg").style.backgroundImage =
      "url(" + chrome.runtime.getURL(iconPath) + ")";
    // Use Chrome's definition of UI language instead of PDF.js's #lang=...,
    // because the shown string should match the UI at chrome://extensions.
    // These strings are from chrome/app/resources/generated_resources_*.xtb.
-    let i18nFileAccessLabel = PDFJSDev.json(
+    const i18nFileAccessLabel = PDFJSDev.json(
      "$ROOT/web/chrome-i18n-allow-access-to-file-urls.json"
    )[chrome.i18n.getUILanguage && chrome.i18n.getUILanguage()];
@ -188,7 +188,7 @@ function requestAccessToLocalFile(fileUrl, overlayManager, callback) {
      ).textContent = i18nFileAccessLabel;
    }
-    let link = document.getElementById("chrome-link-to-extensions-page");
+    const link = document.getElementById("chrome-link-to-extensions-page");
    link.href = "chrome://extensions/?id=" + chrome.runtime.id;
    link.onclick = function(e) {
      // Direct navigation to chrome:// URLs is blocked by Chrome, so we
@ -207,12 +207,12 @@ function requestAccessToLocalFile(fileUrl, overlayManager, callback) {
    document.getElementById("chrome-url-of-local-file").textContent = fileUrl;
    document.getElementById("chrome-file-fallback").onchange = function() {
-      let file = this.files[0];
+      const file = this.files[0];
      if (file) {
-        let originalFilename = decodeURIComponent(fileUrl.split("/").pop());
+        const originalFilename = decodeURIComponent(fileUrl.split("/").pop());
        let originalUrl = fileUrl;
        if (originalFilename !== file.name) {
-          let msg =
+          const msg =
            "The selected file does not match the original file." +
            "\nOriginal: " +
            originalFilename +
@ -288,7 +288,7 @@ function setReferer(url, callback) {
      // back and forward, the background page will not observe a HTTP request
      // with Referer. To make sure that the Referer is preserved, store it in
      // history.state, which is preserved across reloads/navigations.
-      let state = window.history.state || {};
+      const state = window.history.state || {};
      state.chromecomState = referer;
      window.history.replaceState(state, "");
    }
@ -309,13 +309,13 @@ function setReferer(url, callback) {
 // chrome.storage.sync is not supported in every Chromium-derivate.
 // Note: The background page takes care of migrating values from
 // chrome.storage.local to chrome.storage.sync when needed.
-let storageArea = chrome.storage.sync || chrome.storage.local;
+const storageArea = chrome.storage.sync || chrome.storage.local;
 class ChromePreferences extends BasePreferences {
  async _writeToStorage(prefObj) {
    return new Promise(resolve => {
      if (prefObj === this.defaults) {
-        let keysToRemove = Object.keys(this.defaults);
+        const keysToRemove = Object.keys(this.defaults);
        // If the storage is reset, remove the keys so that the values from
        // managed storage are applied again.
        storageArea.remove(keysToRemove, function() {
@ -331,7 +331,7 @@ class ChromePreferences extends BasePreferences {
  async _readFromStorage(prefObj) {
    return new Promise(resolve => {
-      let getPreferences = defaultPrefs => {
+      const getPreferences = defaultPrefs => {
        if (chrome.runtime.lastError) {
          // Managed storage not supported, e.g. in Opera.
          defaultPrefs = this.defaults;
@ -349,7 +349,7 @@ class ChromePreferences extends BasePreferences {
        // Deprecated preferences are removed from web/default_preferences.json,
        // but kept in extensions/chromium/preferences_schema.json for backwards
        // compatibility with managed preferences.
-        let defaultManagedPrefs = Object.assign(
+        const defaultManagedPrefs = Object.assign(
          {
            enableHandToolOnLoad: false,
            disableTextLayer: false,
@ -404,9 +404,9 @@ class ChromePreferences extends BasePreferences {
  }
 }
-let ChromeExternalServices = Object.create(DefaultExternalServices);
+const ChromeExternalServices = Object.create(DefaultExternalServices);
 ChromeExternalServices.initPassiveLoading = function(callbacks) {
-  let { overlayManager } = PDFViewerApplication;
+  const { overlayManager } = PDFViewerApplication;
  // defaultUrl is set in viewer.js
  ChromeCom.resolvePDFFile(
    AppOptions.get("defaultUrl"),
--- a/web/debugger.js
+++ b/web/debugger.js
@ -21,20 +21,22 @@ var FontInspector = (function FontInspectorClosure() {
  var active = false;
  var fontAttribute = "data-font-name";
  function removeSelection() {
-    let divs = document.querySelectorAll(`span[${fontAttribute}]`);
+    const divs = document.querySelectorAll(`span[${fontAttribute}]`);
-    for (let div of divs) {
+    for (const div of divs) {
      div.className = "";
    }
  }
  function resetSelection() {
-    let divs = document.querySelectorAll(`span[${fontAttribute}]`);
+    const divs = document.querySelectorAll(`span[${fontAttribute}]`);
-    for (let div of divs) {
+    for (const div of divs) {
      div.className = "debuggerHideText";
    }
  }
  function selectFont(fontName, show) {
-    let divs = document.querySelectorAll(`span[${fontAttribute}=${fontName}]`);
+    const divs = document.querySelectorAll(
-    for (let div of divs) {
+      `span[${fontAttribute}=${fontName}]`
    );
    for (const div of divs) {
      div.className = show ? "debuggerShowText" : "debuggerHideText";
    }
  }
--- a/web/download_manager.js
+++ b/web/download_manager.js
@ -30,7 +30,7 @@ const DISABLE_CREATE_OBJECT_URL =
  apiCompatibilityParams.disableCreateObjectURL || false;
 function download(blobUrl, filename) {
-  let a = document.createElement("a");
+  const a = document.createElement("a");
  if (!a.click) {
    throw new Error('DownloadManager: "a.click()" is not supported.');
  }
@ -66,7 +66,7 @@ class DownloadManager {
      navigator.msSaveBlob(new Blob([data], { type: contentType }), filename);
      return;
    }
-    let blobUrl = createObjectURL(
+    const blobUrl = createObjectURL(
      data,
      contentType,
      this.disableCreateObjectURL
@ -89,7 +89,7 @@ class DownloadManager {
      return;
    }
-    let blobUrl = URL.createObjectURL(blob);
+    const blobUrl = URL.createObjectURL(blob);
    download(blobUrl, filename);
  }
 }
--- a/web/firefox_print_service.js
+++ b/web/firefox_print_service.js
@ -20,7 +20,7 @@ import { shadow } from "pdfjs-lib";
 // Creates a placeholder with div and canvas with right size for the page.
 function composePage(pdfDocument, pageNumber, size, printContainer) {
-  let canvas = document.createElement("canvas");
+  const canvas = document.createElement("canvas");
  // The size of the canvas in pixels for printing.
  const PRINT_RESOLUTION = AppOptions.get("printResolution") || 150;
@ -32,13 +32,13 @@ function composePage(pdfDocument, pageNumber, size, printContainer) {
  canvas.style.width = Math.floor(size.width * CSS_UNITS) + "px";
  canvas.style.height = Math.floor(size.height * CSS_UNITS) + "px";
-  let canvasWrapper = document.createElement("div");
+  const canvasWrapper = document.createElement("div");
  canvasWrapper.appendChild(canvas);
  printContainer.appendChild(canvasWrapper);
  canvas.mozPrintCallback = function(obj) {
    // Printing/rendering the page.
-    let ctx = obj.context;
+    const ctx = obj.context;
    ctx.save();
    ctx.fillStyle = "rgb(255, 255, 255)";
@ -48,7 +48,7 @@ function composePage(pdfDocument, pageNumber, size, printContainer) {
    pdfDocument
      .getPage(pageNumber)
      .then(function(pdfPage) {
-        let renderContext = {
+        const renderContext = {
          canvasContext: ctx,
          transform: [PRINT_UNITS, 0, 0, PRINT_UNITS, 0, 0],
          viewport: pdfPage.getViewport({ scale: 1, rotation: size.rotation }),
@ -103,8 +103,8 @@ FirefoxPrintService.prototype = {
 PDFPrintServiceFactory.instance = {
  get supportsPrinting() {
-    let canvas = document.createElement("canvas");
+    const canvas = document.createElement("canvas");
-    let value = "mozPrintCallback" in canvas;
+    const value = "mozPrintCallback" in canvas;
    return shadow(this, "supportsPrinting", value);
  },
--- a/web/firefoxcom.js
+++ b/web/firefoxcom.js
@ -29,7 +29,7 @@ if (
  );
 }
-let FirefoxCom = (function FirefoxComClosure() {
+const FirefoxCom = (function FirefoxComClosure() {
  return {
    /**
     * Creates an event that the extension is listening for and will
@ -41,17 +41,17 @@ let FirefoxCom = (function FirefoxComClosure() {
     * @returns {*} The response.
     */
    requestSync(action, data) {
-      let request = document.createTextNode("");
+      const request = document.createTextNode("");
      document.documentElement.appendChild(request);
-      let sender = document.createEvent("CustomEvent");
+      const sender = document.createEvent("CustomEvent");
      sender.initCustomEvent("pdf.js.message", true, false, {
        action,
        data,
        sync: true,
      });
      request.dispatchEvent(sender);
-      let response = sender.detail.response;
+      const response = sender.detail.response;
      document.documentElement.removeChild(request);
      return response;
    },
@ -65,11 +65,11 @@ let FirefoxCom = (function FirefoxComClosure() {
     *   with one data argument.
     */
    request(action, data, callback) {
-      let request = document.createTextNode("");
+      const request = document.createTextNode("");
      if (callback) {
        document.addEventListener("pdf.js.response", function listener(event) {
-          let node = event.target;
+          const node = event.target;
-          let response = event.detail.response;
+          const response = event.detail.response;
          document.documentElement.removeChild(node);
@ -79,7 +79,7 @@ let FirefoxCom = (function FirefoxComClosure() {
      }
      document.documentElement.appendChild(request);
-      let sender = document.createEvent("CustomEvent");
+      const sender = document.createEvent("CustomEvent");
      sender.initCustomEvent("pdf.js.message", true, false, {
        action,
        data,
@ -104,7 +104,7 @@ class DownloadManager {
  }
  downloadData(data, filename, contentType) {
-    let blobUrl = createObjectURL(data, contentType);
+    const blobUrl = createObjectURL(data, contentType);
    FirefoxCom.request("download", {
      blobUrl,
@ -115,8 +115,8 @@ class DownloadManager {
  }
  download(blob, url, filename) {
-    let blobUrl = URL.createObjectURL(blob);
+    const blobUrl = URL.createObjectURL(blob);
-    let onResponse = err => {
+    const onResponse = err => {
      if (err && this.onerror) {
        this.onerror(err);
      }
@ -145,7 +145,7 @@ class FirefoxPreferences extends BasePreferences {
  async _readFromStorage(prefObj) {
    return new Promise(function(resolve) {
      FirefoxCom.request("getPreferences", prefObj, function(prefStr) {
-        let readPrefs = JSON.parse(prefStr);
+        const readPrefs = JSON.parse(prefStr);
        resolve(readPrefs);
      });
    });
@ -259,7 +259,7 @@ PDFViewerApplication.externalServices = {
        console.warn("Rejected untrusted message from " + e.origin);
        return;
      }
-      let args = e.data;
+      const args = e.data;
      if (typeof args !== "object" || !("pdfjsLoadAction" in args)) {
        return;
@ -328,28 +328,30 @@ PDFViewerApplication.externalServices = {
  },
  createL10n(options) {
-    let mozL10n = document.mozL10n;
+    const mozL10n = document.mozL10n;
    // TODO refactor mozL10n.setExternalLocalizerServices
    return new MozL10n(mozL10n);
  },
  get supportsIntegratedFind() {
-    let support = FirefoxCom.requestSync("supportsIntegratedFind");
+    const support = FirefoxCom.requestSync("supportsIntegratedFind");
    return shadow(this, "supportsIntegratedFind", support);
  },
  get supportsDocumentFonts() {
-    let support = FirefoxCom.requestSync("supportsDocumentFonts");
+    const support = FirefoxCom.requestSync("supportsDocumentFonts");
    return shadow(this, "supportsDocumentFonts", support);
  },
  get supportsDocumentColors() {
-    let support = FirefoxCom.requestSync("supportsDocumentColors");
+    const support = FirefoxCom.requestSync("supportsDocumentColors");
    return shadow(this, "supportsDocumentColors", support);
  },
  get supportedMouseWheelZoomModifierKeys() {
-    let support = FirefoxCom.requestSync("supportedMouseWheelZoomModifierKeys");
+    const support = FirefoxCom.requestSync(
      "supportedMouseWheelZoomModifierKeys"
    );
    return shadow(this, "supportedMouseWheelZoomModifierKeys", support);
  },
 };
--- a/web/genericcom.js
+++ b/web/genericcom.js
@ -25,7 +25,7 @@ if (typeof PDFJSDev !== "undefined" && !PDFJSDev.test("GENERIC")) {
  );
 }
-let GenericCom = {};
+const GenericCom = {};
 class GenericPreferences extends BasePreferences {
  async _writeToStorage(prefObj) {
@ -37,7 +37,7 @@ class GenericPreferences extends BasePreferences {
  }
 }
-let GenericExternalServices = Object.create(DefaultExternalServices);
+const GenericExternalServices = Object.create(DefaultExternalServices);
 GenericExternalServices.createDownloadManager = function(options) {
  return new DownloadManager(options);
 };
--- a/web/genericl10n.js
+++ b/web/genericl10n.js
@ -15,7 +15,7 @@
 import "../external/webL10n/l10n";
-let webL10n = document.webL10n;
+const webL10n = document.webL10n;
 class GenericL10n {
  constructor(lang) {
--- a/web/password_prompt.js
+++ b/web/password_prompt.js
@ -97,7 +97,7 @@ class PasswordPrompt {
  }
  verify() {
-    let password = this.input.value;
+    const password = this.input.value;
    if (password && password.length > 0) {
      this.close();
      this.updateCallback(password);
--- a/web/pdf_attachment_viewer.js
+++ b/web/pdf_attachment_viewer.js
@ -135,18 +135,18 @@ class PDFAttachmentViewer {
      return;
    }
-    let names = Object.keys(attachments).sort(function(a, b) {
+    const names = Object.keys(attachments).sort(function(a, b) {
      return a.toLowerCase().localeCompare(b.toLowerCase());
    });
    attachmentsCount = names.length;
    for (let i = 0; i < attachmentsCount; i++) {
-      let item = attachments[names[i]];
+      const item = attachments[names[i]];
-      let filename = removeNullCharacters(getFilenameFromUrl(item.filename));
+      const filename = removeNullCharacters(getFilenameFromUrl(item.filename));
-      let div = document.createElement("div");
+      const div = document.createElement("div");
      div.className = "attachmentsItem";
-      let button = document.createElement("button");
+      const button = document.createElement("button");
      button.textContent = filename;
      if (
        /\.pdf$/i.test(filename) &&
@ -175,7 +175,7 @@ class PDFAttachmentViewer {
      if (!attachments) {
        attachments = Object.create(null);
      } else {
-        for (let name in attachments) {
+        for (const name in attachments) {
          if (id === name) {
            return; // Ignore the new attachment if it already exists.
          }
--- a/web/pdf_cursor_tools.js
+++ b/web/pdf_cursor_tools.js
@ -74,7 +74,7 @@ class PDFCursorTools {
      return; // The requested tool is already active.
    }
-    let disableActiveTool = () => {
+    const disableActiveTool = () => {
      switch (this.active) {
        case CursorTool.SELECT:
          break;
--- a/web/pdf_document_properties.js
+++ b/web/pdf_document_properties.js
@ -102,7 +102,7 @@ class PDFDocumentProperties {
   * Open the document properties overlay.
   */
  open() {
-    let freezeFieldData = data => {
+    const freezeFieldData = data => {
      Object.defineProperty(this, "fieldData", {
        value: Object.freeze(data),
        writable: false,
@ -193,7 +193,7 @@ class PDFDocumentProperties {
          if (fileSize === this.fieldData["fileSize"]) {
            return; // The fileSize has already been correctly set.
          }
-          let data = Object.assign(Object.create(null), this.fieldData);
+          const data = Object.assign(Object.create(null), this.fieldData);
          data["fileSize"] = fileSize;
          freezeFieldData(data);
@ -267,7 +267,7 @@ class PDFDocumentProperties {
   */
  _updateUI(reset = false) {
    if (reset || !this.fieldData) {
-      for (let id in this.fields) {
+      for (const id in this.fields) {
        this.fields[id].textContent = DEFAULT_FIELD_CONTENT;
      }
      return;
@ -277,8 +277,8 @@ class PDFDocumentProperties {
      // since it will be updated the next time `this.open` is called.
      return;
    }
-    for (let id in this.fields) {
+    for (const id in this.fields) {
-      let content = this.fieldData[id];
+      const content = this.fieldData[id];
      this.fields[id].textContent =
        content || content === 0 ? content : DEFAULT_FIELD_CONTENT;
    }
@ -288,7 +288,7 @@ class PDFDocumentProperties {
   * @private
   */
  async _parseFileSize(fileSize = 0) {
-    let kb = fileSize / 1024;
+    const kb = fileSize / 1024;
    if (!kb) {
      return undefined;
    } else if (kb < 1024) {
--- a/web/pdf_find_bar.js
+++ b/web/pdf_find_bar.js
@ -153,8 +153,8 @@ class PDFFindBar {
    if (!this.findResultsCount) {
      return; // No UI control is provided.
    }
-    let matchesCountMsg = "",
+    const limit = MATCHES_COUNT_LIMIT;
-      limit = MATCHES_COUNT_LIMIT;
+    let matchesCountMsg = "";
    if (total > 0) {
      if (total > limit) {
@ -255,8 +255,8 @@ class PDFFindBar {
    // wrapped). Here we detect and fix that.
    this.bar.classList.remove("wrapContainers");
-    let findbarHeight = this.bar.clientHeight;
+    const findbarHeight = this.bar.clientHeight;
-    let inputContainerHeight = this.bar.firstElementChild.clientHeight;
+    const inputContainerHeight = this.bar.firstElementChild.clientHeight;
    if (findbarHeight > inputContainerHeight) {
      // The findbar is taller than the input container, which means that
--- a/web/pdf_history.js
+++ b/web/pdf_history.js
@ -136,7 +136,7 @@ class PDFHistory {
    // The browser history contains a valid entry, ensure that the history is
    // initialized correctly on PDF document load.
-    let destination = state.destination;
+    const destination = state.destination;
    this._updateInternalState(
      destination,
      state.uid,
@ -221,7 +221,7 @@ class PDFHistory {
      }
    }
-    let hash = namedDest || JSON.stringify(explicitDest);
+    const hash = namedDest || JSON.stringify(explicitDest);
    if (!hash) {
      // The hash *should* never be undefined, but if that were to occur,
      // avoid any possible issues by not updating the browser history.
@ -288,7 +288,7 @@ class PDFHistory {
    if (!this._initialized || this._popStateInProgress) {
      return;
    }
-    let state = window.history.state;
+    const state = window.history.state;
    if (this._isValidState(state) && state.uid > 0) {
      window.history.back();
    }
@ -302,7 +302,7 @@ class PDFHistory {
    if (!this._initialized || this._popStateInProgress) {
      return;
    }
-    let state = window.history.state;
+    const state = window.history.state;
    if (this._isValidState(state) && state.uid < this._maxUid) {
      window.history.forward();
    }
@ -331,8 +331,8 @@ class PDFHistory {
   * @private
   */
  _pushOrReplaceState(destination, forceReplace = false) {
-    let shouldReplace = forceReplace || !this._destination;
+    const shouldReplace = forceReplace || !this._destination;
-    let newState = {
+    const newState = {
      fingerprint: this._fingerprint,
      uid: shouldReplace ? this._uid : this._uid + 1,
      destination,
@ -575,7 +575,7 @@ class PDFHistory {
   * @private
   */
  _popState({ state }) {
-    let newHash = getCurrentHash(),
+    const newHash = getCurrentHash(),
      hashChanged = this._currentHash !== newHash;
    this._currentHash = newHash;
@ -628,7 +628,7 @@ class PDFHistory {
    }
    // Navigate to the new destination.
-    let destination = state.destination;
+    const destination = state.destination;
    this._updateInternalState(
      destination,
      state.uid,
@ -711,7 +711,7 @@ function isDestHashesEqual(destHash, pushHash) {
  if (destHash === pushHash) {
    return true;
  }
-  let { nameddest } = parseQueryString(destHash);
+  const { nameddest } = parseQueryString(destHash);
  if (nameddest === pushHash) {
    return true;
  }
@ -730,7 +730,7 @@ function isDestArraysEqual(firstDest, secondDest) {
      if (Object.keys(first).length !== Object.keys(second).length) {
        return false;
      }
-      for (let key in first) {
+      for (const key in first) {
        if (!isEntryEqual(first[key], second[key])) {
          return false;
        }
--- a/web/pdf_link_service.js
+++ b/web/pdf_link_service.js
@ -106,10 +106,10 @@ class PDFLinkService {
   * @param {string|Array} dest - The named, or explicit, PDF destination.
   */
  navigateTo(dest) {
-    let goToDestination = ({ namedDest, explicitDest }) => {
+    const goToDestination = ({ namedDest, explicitDest }) => {
      // Dest array looks like that: <page-ref> </XYZ|/FitXXX> <args..>
-      let destRef = explicitDest[0],
+      const destRef = explicitDest[0];
-        pageNumber;
+      let pageNumber;
      if (destRef instanceof Object) {
        pageNumber = this._cachedPageNumber(destRef);
@ -196,7 +196,7 @@ class PDFLinkService {
      return this.getAnchorUrl("#" + escape(dest));
    }
    if (Array.isArray(dest)) {
-      let str = JSON.stringify(dest);
+      const str = JSON.stringify(dest);
      return this.getAnchorUrl("#" + escape(str));
    }
    return this.getAnchorUrl("");
@ -218,7 +218,7 @@ class PDFLinkService {
  setHash(hash) {
    let pageNumber, dest;
    if (hash.includes("=")) {
-      let params = parseQueryString(hash);
+      const params = parseQueryString(hash);
      if ("search" in params) {
        this.eventBus.dispatch("findfromurlhash", {
          source: this,
@ -236,9 +236,9 @@ class PDFLinkService {
      }
      if ("zoom" in params) {
        // Build the destination array.
-        let zoomArgs = params.zoom.split(","); // scale,left,top
+        const zoomArgs = params.zoom.split(","); // scale,left,top
-        let zoomArg = zoomArgs[0];
+        const zoomArg = zoomArgs[0];
-        let zoomArgNumber = parseFloat(zoomArg);
+        const zoomArgNumber = parseFloat(zoomArg);
        if (!zoomArg.includes("Fit")) {
          // If the zoomArg is a number, it has to get divided by 100. If it's
@ -405,12 +405,11 @@ function isValidExplicitDestination(dest) {
  if (!Array.isArray(dest)) {
    return false;
  }
-  let destLength = dest.length,
+  const destLength = dest.length;
    allowNull = true;
  if (destLength < 2) {
    return false;
  }
-  let page = dest[0];
+  const page = dest[0];
  if (
    !(
      typeof page === "object" &&
@ -421,10 +420,11 @@ function isValidExplicitDestination(dest) {
  ) {
    return false;
  }
-  let zoom = dest[1];
+  const zoom = dest[1];
  if (!(typeof zoom === "object" && typeof zoom.name === "string")) {
    return false;
  }
  let allowNull = true;
  switch (zoom.name) {
    case "XYZ":
      if (destLength !== 5) {
@ -452,7 +452,7 @@ function isValidExplicitDestination(dest) {
      return false;
  }
  for (let i = 2; i < destLength; i++) {
-    let param = dest[i];
+    const param = dest[i];
    if (!(typeof param === "number" || (allowNull && param === null))) {
      return false;
    }
--- a/web/pdf_outline_viewer.js
+++ b/web/pdf_outline_viewer.js
@ -69,7 +69,7 @@ class PDFOutlineViewer {
   * @private
   */
  _bindLink(element, { url, newWindow, dest }) {
-    let { linkService } = this;
+    const { linkService } = this;
    if (url) {
      addLinkAttributes(element, {
@ -114,7 +114,7 @@ class PDFOutlineViewer {
   * @private
   */
  _addToggleButton(div, { count, items }) {
-    let toggler = document.createElement("div");
+    const toggler = document.createElement("div");
    toggler.className = "outlineItemToggler";
    if (count < 0 && Math.abs(count) === items.length) {
      toggler.classList.add("outlineItemsHidden");
@ -124,7 +124,7 @@ class PDFOutlineViewer {
      toggler.classList.toggle("outlineItemsHidden");
      if (evt.shiftKey) {
-        let shouldShowAll = !toggler.classList.contains("outlineItemsHidden");
+        const shouldShowAll = !toggler.classList.contains("outlineItemsHidden");
        this._toggleOutlineItem(div, shouldShowAll);
      }
    };
@ -173,16 +173,16 @@ class PDFOutlineViewer {
      return;
    }
-    let fragment = document.createDocumentFragment();
+    const fragment = document.createDocumentFragment();
-    let queue = [{ parent: fragment, items: this.outline }];
+    const queue = [{ parent: fragment, items: this.outline }];
    let hasAnyNesting = false;
    while (queue.length > 0) {
      const levelData = queue.shift();
      for (const item of levelData.items) {
-        let div = document.createElement("div");
+        const div = document.createElement("div");
        div.className = "outlineItem";
-        let element = document.createElement("a");
+        const element = document.createElement("a");
        this._bindLink(element, item);
        this._setStyles(element, item);
        element.textContent = removeNullCharacters(item.title) || DEFAULT_TITLE;
@ -193,7 +193,7 @@ class PDFOutlineViewer {
          hasAnyNesting = true;
          this._addToggleButton(div, item);
-          let itemsDiv = document.createElement("div");
+          const itemsDiv = document.createElement("div");
          itemsDiv.className = "outlineItems";
          div.appendChild(itemsDiv);
          queue.push({ parent: itemsDiv, items: item.items });
--- a/web/pdf_page_view.js
+++ b/web/pdf_page_view.js
@ -71,8 +71,8 @@ class PDFPageView {
   * @param {PDFPageViewOptions} options
   */
  constructor(options) {
-    let container = options.container;
+    const container = options.container;
-    let defaultViewport = options.defaultViewport;
+    const defaultViewport = options.defaultViewport;
    this.id = options.id;
    this.renderingId = "page" + this.id;
@ -110,7 +110,7 @@ class PDFPageView {
    this.textLayer = null;
    this.zoomLayer = null;
-    let div = document.createElement("div");
+    const div = document.createElement("div");
    div.className = "page";
    div.style.width = Math.floor(this.viewport.width) + "px";
    div.style.height = Math.floor(this.viewport.height) + "px";
@ -124,7 +124,7 @@ class PDFPageView {
    this.pdfPage = pdfPage;
    this.pdfPageRotate = pdfPage.rotate;
-    let totalRotation = (this.rotation + this.pdfPageRotate) % 360;
+    const totalRotation = (this.rotation + this.pdfPageRotate) % 360;
    this.viewport = pdfPage.getViewport({
      scale: this.scale * CSS_UNITS,
      rotation: totalRotation,
@ -147,7 +147,7 @@ class PDFPageView {
    if (!this.zoomLayer) {
      return;
    }
-    let zoomLayerCanvas = this.zoomLayer.firstChild;
+    const zoomLayerCanvas = this.zoomLayer.firstChild;
    this.paintedViewportMap.delete(zoomLayerCanvas);
    // Zeroing the width and height causes Firefox to release graphics
    // resources immediately, which can greatly reduce memory consumption.
@ -165,17 +165,17 @@ class PDFPageView {
    this.cancelRendering(keepAnnotations);
    this.renderingState = RenderingStates.INITIAL;
-    let div = this.div;
+    const div = this.div;
    div.style.width = Math.floor(this.viewport.width) + "px";
    div.style.height = Math.floor(this.viewport.height) + "px";
-    let childNodes = div.childNodes;
+    const childNodes = div.childNodes;
-    let currentZoomLayerNode = (keepZoomLayer && this.zoomLayer) || null;
+    const currentZoomLayerNode = (keepZoomLayer && this.zoomLayer) || null;
-    let currentAnnotationNode =
+    const currentAnnotationNode =
      (keepAnnotations && this.annotationLayer && this.annotationLayer.div) ||
      null;
    for (let i = childNodes.length - 1; i >= 0; i--) {
-      let node = childNodes[i];
+      const node = childNodes[i];
      if (currentZoomLayerNode === node || currentAnnotationNode === node) {
        continue;
      }
@ -220,7 +220,7 @@ class PDFPageView {
      this.rotation = rotation;
    }
-    let totalRotation = (this.rotation + this.pdfPageRotate) % 360;
+    const totalRotation = (this.rotation + this.pdfPageRotate) % 360;
    this.viewport = this.viewport.clone({
      scale: this.scale * CSS_UNITS,
      rotation: totalRotation,
@ -240,7 +240,7 @@ class PDFPageView {
    let isScalingRestricted = false;
    if (this.canvas && this.maxCanvasPixels > 0) {
-      let outputScale = this.outputScale;
+      const outputScale = this.outputScale;
      if (
        ((Math.floor(this.viewport.width) * outputScale.sx) | 0) *
          ((Math.floor(this.viewport.height) * outputScale.sy) | 0) >
@ -299,17 +299,17 @@ class PDFPageView {
  cssTransform(target, redrawAnnotations = false) {
    // Scale target (canvas or svg), its wrapper and page container.
-    let width = this.viewport.width;
+    const width = this.viewport.width;
-    let height = this.viewport.height;
+    const height = this.viewport.height;
-    let div = this.div;
+    const div = this.div;
    target.style.width = target.parentNode.style.width = div.style.width =
      Math.floor(width) + "px";
    target.style.height = target.parentNode.style.height = div.style.height =
      Math.floor(height) + "px";
    // The canvas may have been originally rotated; rotate relative to that.
-    let relativeRotation =
+    const relativeRotation =
      this.viewport.rotation - this.paintedViewportMap.get(target).rotation;
-    let absRotation = Math.abs(relativeRotation);
+    const absRotation = Math.abs(relativeRotation);
    let scaleX = 1,
      scaleY = 1;
    if (absRotation === 90 || absRotation === 270) {
@ -317,7 +317,7 @@ class PDFPageView {
      scaleX = height / width;
      scaleY = width / height;
    }
-    let cssTransform =
+    const cssTransform =
      "rotate(" +
      relativeRotation +
      "deg) " +
@ -333,15 +333,15 @@ class PDFPageView {
      // the text layer are rotated.
      // TODO: This could probably be simplified by drawing the text layer in
      // one orientation and then rotating overall.
-      let textLayerViewport = this.textLayer.viewport;
+      const textLayerViewport = this.textLayer.viewport;
-      let textRelativeRotation =
+      const textRelativeRotation =
        this.viewport.rotation - textLayerViewport.rotation;
-      let textAbsRotation = Math.abs(textRelativeRotation);
+      const textAbsRotation = Math.abs(textRelativeRotation);
      let scale = width / textLayerViewport.width;
      if (textAbsRotation === 90 || textAbsRotation === 270) {
        scale = width / textLayerViewport.height;
      }
-      let textLayerDiv = this.textLayer.textLayerDiv;
+      const textLayerDiv = this.textLayer.textLayerDiv;
      let transX, transY;
      switch (textAbsRotation) {
        case 0:
@ -411,11 +411,11 @@ class PDFPageView {
    this.renderingState = RenderingStates.RUNNING;
-    let pdfPage = this.pdfPage;
+    const pdfPage = this.pdfPage;
-    let div = this.div;
+    const div = this.div;
    // Wrap the canvas so that if it has a CSS transform for high DPI the
    // overflow will be hidden in Firefox.
-    let canvasWrapper = document.createElement("div");
+    const canvasWrapper = document.createElement("div");
    canvasWrapper.style.width = div.style.width;
    canvasWrapper.style.height = div.style.height;
    canvasWrapper.classList.add("canvasWrapper");
@ -429,7 +429,7 @@ class PDFPageView {
    let textLayer = null;
    if (this.textLayerMode !== TextLayerMode.DISABLE && this.textLayerFactory) {
-      let textLayerDiv = document.createElement("div");
+      const textLayerDiv = document.createElement("div");
      textLayerDiv.className = "textLayer";
      textLayerDiv.style.width = canvasWrapper.style.width;
      textLayerDiv.style.height = canvasWrapper.style.height;
@ -500,18 +500,18 @@ class PDFPageView {
      }
    };
-    let paintTask =
+    const paintTask =
      this.renderer === RendererType.SVG
        ? this.paintOnSvg(canvasWrapper)
        : this.paintOnCanvas(canvasWrapper);
    paintTask.onRenderContinue = renderContinueCallback;
    this.paintTask = paintTask;
-    let resultPromise = paintTask.promise.then(
+    const resultPromise = paintTask.promise.then(
      function() {
        return finishPaintTask(null).then(function() {
          if (textLayer) {
-            let readableStream = pdfPage.streamTextContent({
+            const readableStream = pdfPage.streamTextContent({
              normalizeWhitespace: true,
            });
            textLayer.setTextContentStream(readableStream);
@ -546,8 +546,8 @@ class PDFPageView {
  }
  paintOnCanvas(canvasWrapper) {
-    let renderCapability = createPromiseCapability();
+    const renderCapability = createPromiseCapability();
-    let result = {
+    const result = {
      promise: renderCapability.promise,
      onRenderContinue(cont) {
        cont();
@ -557,15 +557,15 @@ class PDFPageView {
      },
    };
-    let viewport = this.viewport;
+    const viewport = this.viewport;
-    let canvas = document.createElement("canvas");
+    const canvas = document.createElement("canvas");
    canvas.id = this.renderingId;
    // Keep the canvas hidden until the first draw callback, or until drawing
    // is complete when `!this.renderingQueue`, to prevent black flickering.
    canvas.setAttribute("hidden", "hidden");
    let isCanvasHidden = true;
-    let showCanvas = function() {
+    const showCanvas = function() {
      if (isCanvasHidden) {
        canvas.removeAttribute("hidden");
        isCanvasHidden = false;
@ -582,12 +582,12 @@ class PDFPageView {
      canvas.mozOpaque = true;
    }
-    let ctx = canvas.getContext("2d", { alpha: false });
+    const ctx = canvas.getContext("2d", { alpha: false });
-    let outputScale = getOutputScale(ctx);
+    const outputScale = getOutputScale(ctx);
    this.outputScale = outputScale;
    if (this.useOnlyCssZoom) {
-      let actualSizeViewport = viewport.clone({ scale: CSS_UNITS });
+      const actualSizeViewport = viewport.clone({ scale: CSS_UNITS });
      // Use a scale that makes the canvas have the originally intended size
      // of the page.
      outputScale.sx *= actualSizeViewport.width / viewport.width;
@ -596,8 +596,8 @@ class PDFPageView {
    }
    if (this.maxCanvasPixels > 0) {
-      let pixelsInViewport = viewport.width * viewport.height;
+      const pixelsInViewport = viewport.width * viewport.height;
-      let maxScale = Math.sqrt(this.maxCanvasPixels / pixelsInViewport);
+      const maxScale = Math.sqrt(this.maxCanvasPixels / pixelsInViewport);
      if (outputScale.sx > maxScale || outputScale.sy > maxScale) {
        outputScale.sx = maxScale;
        outputScale.sy = maxScale;
@ -608,8 +608,8 @@ class PDFPageView {
      }
    }
-    let sfx = approximateFraction(outputScale.sx);
+    const sfx = approximateFraction(outputScale.sx);
-    let sfy = approximateFraction(outputScale.sy);
+    const sfy = approximateFraction(outputScale.sy);
    canvas.width = roundToDivide(viewport.width * outputScale.sx, sfx[0]);
    canvas.height = roundToDivide(viewport.height * outputScale.sy, sfy[0]);
    canvas.style.width = roundToDivide(viewport.width, sfx[1]) + "px";
@ -618,17 +618,17 @@ class PDFPageView {
    this.paintedViewportMap.set(canvas, viewport);
    // Rendering area
-    let transform = !outputScale.scaled
+    const transform = !outputScale.scaled
      ? null
      : [outputScale.sx, 0, 0, outputScale.sy, 0, 0];
-    let renderContext = {
+    const renderContext = {
      canvasContext: ctx,
      transform,
      viewport: this.viewport,
      enableWebGL: this.enableWebGL,
      renderInteractiveForms: this.renderInteractiveForms,
    };
-    let renderTask = this.pdfPage.render(renderContext);
+    const renderTask = this.pdfPage.render(renderContext);
    renderTask.onContinue = function(cont) {
      showCanvas();
      if (result.onRenderContinue) {
@ -666,7 +666,7 @@ class PDFPageView {
    }
    let cancelled = false;
-    let ensureNotCancelled = () => {
+    const ensureNotCancelled = () => {
      if (cancelled) {
        throw new RenderingCancelledException(
          "Rendering cancelled, page " + this.id,
@ -675,11 +675,11 @@ class PDFPageView {
      }
    };
-    let pdfPage = this.pdfPage;
+    const pdfPage = this.pdfPage;
-    let actualSizeViewport = this.viewport.clone({ scale: CSS_UNITS });
+    const actualSizeViewport = this.viewport.clone({ scale: CSS_UNITS });
-    let promise = pdfPage.getOperatorList().then(opList => {
+    const promise = pdfPage.getOperatorList().then(opList => {
      ensureNotCancelled();
-      let svgGfx = new SVGGraphics(pdfPage.commonObjs, pdfPage.objs);
+      const svgGfx = new SVGGraphics(pdfPage.commonObjs, pdfPage.objs);
      return svgGfx.getSVG(opList, actualSizeViewport).then(svg => {
        ensureNotCancelled();
        this.svg = svg;
--- a/web/pdf_presentation_mode.js
+++ b/web/pdf_presentation_mode.js
@ -116,9 +116,9 @@ class PDFPresentationMode {
    evt.preventDefault();
-    let delta = normalizeWheelEventDelta(evt);
+    const delta = normalizeWheelEventDelta(evt);
-    let currentTime = new Date().getTime();
+    const currentTime = new Date().getTime();
-    let storedTime = this.mouseScrollTimeStamp;
+    const storedTime = this.mouseScrollTimeStamp;
    // If we've already switched page, avoid accidentally switching again.
    if (
@ -137,9 +137,9 @@ class PDFPresentationMode {
    this.mouseScrollDelta += delta;
    if (Math.abs(this.mouseScrollDelta) >= PAGE_SWITCH_THRESHOLD) {
-      let totalDelta = this.mouseScrollDelta;
+      const totalDelta = this.mouseScrollDelta;
      this._resetMouseScrollState();
-      let success =
+      const success =
        totalDelta > 0 ? this._goToPreviousPage() : this._goToNextPage();
      if (success) {
        this.mouseScrollTimeStamp = currentTime;
@ -160,7 +160,7 @@ class PDFPresentationMode {
   * @private
   */
  _goToPreviousPage() {
-    let page = this.pdfViewer.currentPageNumber;
+    const page = this.pdfViewer.currentPageNumber;
    // If we're at the first page, we don't need to do anything.
    if (page <= 1) {
      return false;
@ -173,7 +173,7 @@ class PDFPresentationMode {
   * @private
   */
  _goToNextPage() {
-    let page = this.pdfViewer.currentPageNumber;
+    const page = this.pdfViewer.currentPageNumber;
    // If we're at the last page, we don't need to do anything.
    if (page >= this.pdfViewer.pagesCount) {
      return false;
@ -254,7 +254,7 @@ class PDFPresentationMode {
   * @private
   */
  _exit() {
-    let page = this.pdfViewer.currentPageNumber;
+    const page = this.pdfViewer.currentPageNumber;
    this.container.classList.remove(ACTIVE_SELECTOR);
    // Ensure that the correct page is scrolled into view when exiting
@ -288,7 +288,7 @@ class PDFPresentationMode {
    if (evt.button === 0) {
      // Enable clicking of links in presentation mode. Note: only links
      // pointing to destinations in the current PDF document work.
-      let isInternalLink =
+      const isInternalLink =
        evt.target.href && evt.target.classList.contains("internalLink");
      if (!isInternalLink) {
        // Unless an internal link was clicked, advance one page.
@ -384,9 +384,9 @@ class PDFPresentationMode {
          return;
        }
        let delta = 0;
-        let dx = this.touchSwipeState.endX - this.touchSwipeState.startX;
+        const dx = this.touchSwipeState.endX - this.touchSwipeState.startX;
-        let dy = this.touchSwipeState.endY - this.touchSwipeState.startY;
+        const dy = this.touchSwipeState.endY - this.touchSwipeState.startY;
-        let absAngle = Math.abs(Math.atan2(dy, dx));
+        const absAngle = Math.abs(Math.atan2(dy, dx));
        if (
          Math.abs(dx) > SWIPE_MIN_DISTANCE_THRESHOLD &&
          (absAngle <= SWIPE_ANGLE_THRESHOLD ||
--- a/web/pdf_print_service.js
+++ b/web/pdf_print_service.js
@ -23,7 +23,7 @@ let overlayManager = null;
 // Renders the page to the canvas of the given print service, and returns
 // the suggested dimensions of the output page.
 function renderPage(activeServiceOnEntry, pdfDocument, pageNumber, size) {
-  let scratchCanvas = activeService.scratchCanvas;
+  const scratchCanvas = activeService.scratchCanvas;
  // The size of the canvas in pixels for printing.
  const PRINT_RESOLUTION = AppOptions.get("printResolution") || 150;
@ -32,10 +32,10 @@ function renderPage(activeServiceOnEntry, pdfDocument, pageNumber, size) {
  scratchCanvas.height = Math.floor(size.height * PRINT_UNITS);
  // The physical size of the img as specified by the PDF document.
-  let width = Math.floor(size.width * CSS_UNITS) + "px";
+  const width = Math.floor(size.width * CSS_UNITS) + "px";
-  let height = Math.floor(size.height * CSS_UNITS) + "px";
+  const height = Math.floor(size.height * CSS_UNITS) + "px";
-  let ctx = scratchCanvas.getContext("2d");
+  const ctx = scratchCanvas.getContext("2d");
  ctx.save();
  ctx.fillStyle = "rgb(255, 255, 255)";
  ctx.fillRect(0, 0, scratchCanvas.width, scratchCanvas.height);
@ -44,7 +44,7 @@ function renderPage(activeServiceOnEntry, pdfDocument, pageNumber, size) {
  return pdfDocument
    .getPage(pageNumber)
    .then(function(pdfPage) {
-      let renderContext = {
+      const renderContext = {
        canvasContext: ctx,
        transform: [PRINT_UNITS, 0, 0, PRINT_UNITS, 0, 0],
        viewport: pdfPage.getViewport({ scale: 1, rotation: size.rotation }),
@ -79,7 +79,7 @@ PDFPrintService.prototype = {
    const body = document.querySelector("body");
    body.setAttribute("data-pdfjsprinting", true);
-    let hasEqualPageSizes = this.pagesOverview.every(function(size) {
+    const hasEqualPageSizes = this.pagesOverview.every(function(size) {
      return (
        size.width === this.pagesOverview[0].width &&
        size.height === this.pagesOverview[0].height
@ -102,7 +102,7 @@ PDFPrintService.prototype = {
    // https://bugzil.la/851441), the next stylesheet will be ignored and the
    // user has to select the correct paper size in the UI if wanted.
    this.pageStyleSheet = document.createElement("style");
-    let pageSize = this.pagesOverview[0];
+    const pageSize = this.pagesOverview[0];
    this.pageStyleSheet.textContent =
      // "size:<width> <height>" is what we need. But also add "A4" because
      // Firefox incorrectly reports support for the other value.
@ -144,15 +144,15 @@ PDFPrintService.prototype = {
  },
  renderPages() {
-    let pageCount = this.pagesOverview.length;
+    const pageCount = this.pagesOverview.length;
-    let renderNextPage = (resolve, reject) => {
+    const renderNextPage = (resolve, reject) => {
      this.throwIfInactive();
      if (++this.currentPage >= pageCount) {
        renderProgress(pageCount, pageCount, this.l10n);
        resolve();
        return;
      }
-      let index = this.currentPage;
+      const index = this.currentPage;
      renderProgress(index, pageCount, this.l10n);
      renderPage(this, this.pdfDocument, index + 1, this.pagesOverview[index])
        .then(this.useRenderedPage.bind(this))
@ -165,11 +165,11 @@ PDFPrintService.prototype = {
  useRenderedPage(printItem) {
    this.throwIfInactive();
-    let img = document.createElement("img");
+    const img = document.createElement("img");
    img.style.width = printItem.width;
    img.style.height = printItem.height;
-    let scratchCanvas = this.scratchCanvas;
+    const scratchCanvas = this.scratchCanvas;
    if ("toBlob" in scratchCanvas && !this.disableCreateObjectURL) {
      scratchCanvas.toBlob(function(blob) {
        img.src = URL.createObjectURL(blob);
@ -178,7 +178,7 @@ PDFPrintService.prototype = {
      img.src = scratchCanvas.toDataURL();
    }
-    let wrapper = document.createElement("div");
+    const wrapper = document.createElement("div");
    wrapper.appendChild(img);
    this.printContainer.appendChild(wrapper);
@ -217,7 +217,7 @@ PDFPrintService.prototype = {
  },
 };
-let print = window.print;
+const print = window.print;
 window.print = function print() {
  if (activeService) {
    console.warn("Ignored window.print() because of a pending print job.");
@ -241,7 +241,7 @@ window.print = function print() {
      });
      return; // eslint-disable-line no-unsafe-finally
    }
-    let activeServiceOnEntry = activeService;
+    const activeServiceOnEntry = activeService;
    activeService
      .renderPages()
      .then(function() {
@ -264,7 +264,7 @@ window.print = function print() {
 };
 function dispatchEvent(eventType) {
-  let event = document.createEvent("CustomEvent");
+  const event = document.createEvent("CustomEvent");
  event.initCustomEvent(eventType, false, false, "custom");
  window.dispatchEvent(event);
 }
@ -277,10 +277,10 @@ function abort() {
 }
 function renderProgress(index, total, l10n) {
-  let progressContainer = document.getElementById("printServiceOverlay");
+  const progressContainer = document.getElementById("printServiceOverlay");
-  let progress = Math.round((100 * index) / total);
+  const progress = Math.round((100 * index) / total);
-  let progressBar = progressContainer.querySelector("progress");
+  const progressBar = progressContainer.querySelector("progress");
-  let progressPerc = progressContainer.querySelector(".relative-progress");
+  const progressPerc = progressContainer.querySelector(".relative-progress");
  progressBar.value = progress;
  l10n.get("print_progress_percent", { progress }, progress + "%").then(msg => {
    progressPerc.textContent = msg;
@ -316,7 +316,7 @@ window.addEventListener(
 if ("onbeforeprint" in window) {
  // Do not propagate before/afterprint events when they are not triggered
  // from within this polyfill. (FF /IE / Chrome 63+).
-  let stopPropagationIfNeeded = function(event) {
+  const stopPropagationIfNeeded = function(event) {
    if (event.detail !== "custom" && event.stopImmediatePropagation) {
      event.stopImmediatePropagation();
    }
--- a/web/pdf_rendering_queue.js
+++ b/web/pdf_rendering_queue.js
@ -103,14 +103,14 @@ class PDFRenderingQueue {
     * 2. if last scrolled down, the page after the visible pages, or
     *    if last scrolled up, the page before the visible pages
     */
-    let visibleViews = visible.views;
+    const visibleViews = visible.views;
-    let numVisible = visibleViews.length;
+    const numVisible = visibleViews.length;
    if (numVisible === 0) {
      return null;
    }
    for (let i = 0; i < numVisible; ++i) {
-      let view = visibleViews[i].view;
+      const view = visibleViews[i].view;
      if (!this.isViewFinished(view)) {
        return view;
      }
@ -118,13 +118,13 @@ class PDFRenderingQueue {
    // All the visible views have rendered; try to render next/previous pages.
    if (scrolledDown) {
-      let nextPageIndex = visible.last.id;
+      const nextPageIndex = visible.last.id;
      // IDs start at 1, so no need to add 1.
      if (views[nextPageIndex] && !this.isViewFinished(views[nextPageIndex])) {
        return views[nextPageIndex];
      }
    } else {
-      let previousPageIndex = visible.first.id - 2;
+      const previousPageIndex = visible.first.id - 2;
      if (
        views[previousPageIndex] &&
        !this.isViewFinished(views[previousPageIndex])
--- a/web/pdf_sidebar.js
+++ b/web/pdf_sidebar.js
@ -307,14 +307,14 @@ class PDFSidebar {
   * @private
   */
  _updateThumbnailViewer() {
-    let { pdfViewer, pdfThumbnailViewer } = this;
+    const { pdfViewer, pdfThumbnailViewer } = this;
    // Use the rendered pages to set the corresponding thumbnail images.
-    let pagesCount = pdfViewer.pagesCount;
+    const pagesCount = pdfViewer.pagesCount;
    for (let pageIndex = 0; pageIndex < pagesCount; pageIndex++) {
-      let pageView = pdfViewer.getPageView(pageIndex);
+      const pageView = pdfViewer.getPageView(pageIndex);
      if (pageView && pageView.renderingState === RenderingStates.FINISHED) {
-        let thumbnailView = pdfThumbnailViewer.getThumbnail(pageIndex);
+        const thumbnailView = pdfThumbnailViewer.getThumbnail(pageIndex);
        thumbnailView.setImage(pageView);
      }
    }
@ -367,7 +367,7 @@ class PDFSidebar {
      return;
    }
-    let removeNotification = view => {
+    const removeNotification = view => {
      switch (view) {
        case SidebarView.OUTLINE:
          this.outlineButton.classList.remove(UI_NOTIFICATION_CLASS);
@ -431,7 +431,7 @@ class PDFSidebar {
    // Disable/enable views.
    this.eventBus.on("outlineloaded", evt => {
-      let outlineCount = evt.outlineCount;
+      const outlineCount = evt.outlineCount;
      this.outlineButton.disabled = !outlineCount;
--- a/web/pdf_sidebar_resizer.js
+++ b/web/pdf_sidebar_resizer.js
@ -123,7 +123,7 @@ class PDFSidebarResizer {
    // ... and ensure that rendering will always be triggered.
    this.eventBus.dispatch("resize", { source: this });
-    let _boundEvents = this._boundEvents;
+    const _boundEvents = this._boundEvents;
    window.removeEventListener("mousemove", _boundEvents.mouseMove);
    window.removeEventListener("mouseup", _boundEvents.mouseUp);
  }
@ -135,7 +135,7 @@ class PDFSidebarResizer {
    if (!this.enabled) {
      return;
    }
-    let _boundEvents = this._boundEvents;
+    const _boundEvents = this._boundEvents;
    _boundEvents.mouseMove = this._mouseMove.bind(this);
    _boundEvents.mouseUp = this._mouseUp.bind(this);
@ -175,7 +175,7 @@ class PDFSidebarResizer {
        return;
      }
      this.outerContainer.classList.add(SIDEBAR_RESIZING_CLASS);
-      let updated = this._updateWidth(this._width);
+      const updated = this._updateWidth(this._width);
      Promise.resolve().then(() => {
        this.outerContainer.classList.remove(SIDEBAR_RESIZING_CLASS);
--- a/web/pdf_single_page_viewer.js
+++ b/web/pdf_single_page_viewer.js
@ -43,10 +43,10 @@ class PDFSinglePageViewer extends BaseViewer {
  }
  _ensurePageViewVisible() {
-    let pageView = this._pages[this._currentPageNumber - 1];
+    const pageView = this._pages[this._currentPageNumber - 1];
-    let previousPageView = this._pages[this._previousPageNumber - 1];
+    const previousPageView = this._pages[this._previousPageNumber - 1];
-    let viewerNodes = this.viewer.childNodes;
+    const viewerNodes = this.viewer.childNodes;
    switch (viewerNodes.length) {
      case 0: // Should *only* occur on initial loading.
        this.viewer.appendChild(pageView.div);
--- a/web/pdf_thumbnail_view.js
+++ b/web/pdf_thumbnail_view.js
@ -59,7 +59,7 @@ const TempImageFactory = (function TempImageFactoryClosure() {
        tempCanvas.mozOpaque = true;
      }
-      let ctx = tempCanvas.getContext("2d", { alpha: false });
+      const ctx = tempCanvas.getContext("2d", { alpha: false });
      ctx.save();
      ctx.fillStyle = "rgb(255, 255, 255)";
      ctx.fillRect(0, 0, width, height);
@ -68,7 +68,7 @@ const TempImageFactory = (function TempImageFactoryClosure() {
    },
    destroyCanvas() {
-      let tempCanvas = tempCanvasCache;
+      const tempCanvas = tempCanvasCache;
      if (tempCanvas) {
        // Zeroing the width and height causes Firefox to release graphics
        // resources immediately, which can greatly reduce memory consumption.
@ -123,7 +123,7 @@ class PDFThumbnailView {
    this.l10n = l10n;
-    let anchor = document.createElement("a");
+    const anchor = document.createElement("a");
    anchor.href = linkService.getAnchorUrl("#page=" + id);
    this.l10n
      .get("thumb_page_title", { page: id }, "Page {{page}}")
@ -136,14 +136,14 @@ class PDFThumbnailView {
    };
    this.anchor = anchor;
-    let div = document.createElement("div");
+    const div = document.createElement("div");
    div.className = "thumbnail";
    div.setAttribute("data-page-number", this.id);
    this.div = div;
-    let ring = document.createElement("div");
+    const ring = document.createElement("div");
    ring.className = "thumbnailSelectionRing";
-    let borderAdjustment = 2 * THUMBNAIL_CANVAS_BORDER_WIDTH;
+    const borderAdjustment = 2 * THUMBNAIL_CANVAS_BORDER_WIDTH;
    ring.style.width = this.canvasWidth + borderAdjustment + "px";
    ring.style.height = this.canvasHeight + borderAdjustment + "px";
    this.ring = ring;
@ -156,7 +156,7 @@ class PDFThumbnailView {
  setPdfPage(pdfPage) {
    this.pdfPage = pdfPage;
    this.pdfPageRotate = pdfPage.rotate;
-    let totalRotation = (this.rotation + this.pdfPageRotate) % 360;
+    const totalRotation = (this.rotation + this.pdfPageRotate) % 360;
    this.viewport = pdfPage.getViewport({ scale: 1, rotation: totalRotation });
    this.reset();
  }
@ -173,12 +173,12 @@ class PDFThumbnailView {
    this.scale = this.canvasWidth / this.pageWidth;
    this.div.removeAttribute("data-loaded");
-    let ring = this.ring;
+    const ring = this.ring;
-    let childNodes = ring.childNodes;
+    const childNodes = ring.childNodes;
    for (let i = childNodes.length - 1; i >= 0; i--) {
      ring.removeChild(childNodes[i]);
    }
-    let borderAdjustment = 2 * THUMBNAIL_CANVAS_BORDER_WIDTH;
+    const borderAdjustment = 2 * THUMBNAIL_CANVAS_BORDER_WIDTH;
    ring.style.width = this.canvasWidth + borderAdjustment + "px";
    ring.style.height = this.canvasHeight + borderAdjustment + "px";
@ -199,7 +199,7 @@ class PDFThumbnailView {
    if (typeof rotation !== "undefined") {
      this.rotation = rotation;
    }
-    let totalRotation = (this.rotation + this.pdfPageRotate) % 360;
+    const totalRotation = (this.rotation + this.pdfPageRotate) % 360;
    this.viewport = this.viewport.clone({
      scale: 1,
      rotation: totalRotation,
@ -223,7 +223,7 @@ class PDFThumbnailView {
   * @private
   */
  _getPageDrawContext(noCtxScale = false) {
-    let canvas = document.createElement("canvas");
+    const canvas = document.createElement("canvas");
    // Keep the no-thumbnail outline visible, i.e. `data-loaded === false`,
    // until rendering/image conversion is complete, to avoid display issues.
    this.canvas = canvas;
@ -234,8 +234,8 @@ class PDFThumbnailView {
    ) {
      canvas.mozOpaque = true;
    }
-    let ctx = canvas.getContext("2d", { alpha: false });
+    const ctx = canvas.getContext("2d", { alpha: false });
-    let outputScale = getOutputScale(ctx);
+    const outputScale = getOutputScale(ctx);
    canvas.width = (this.canvasWidth * outputScale.sx) | 0;
    canvas.height = (this.canvasHeight * outputScale.sy) | 0;
@ -258,8 +258,8 @@ class PDFThumbnailView {
    if (this.renderingState !== RenderingStates.FINISHED) {
      return;
    }
-    let id = this.renderingId;
+    const id = this.renderingId;
-    let className = "thumbnailImage";
+    const className = "thumbnailImage";
    if (this.disableCanvasToImageConversion) {
      this.canvas.id = id;
@ -278,7 +278,7 @@ class PDFThumbnailView {
      this.ring.appendChild(this.canvas);
      return;
    }
-    let image = document.createElement("img");
+    const image = document.createElement("img");
    image.id = id;
    image.className = className;
    this.l10n
@ -314,8 +314,8 @@ class PDFThumbnailView {
    }
    this.renderingState = RenderingStates.RUNNING;
-    let renderCapability = createPromiseCapability();
+    const renderCapability = createPromiseCapability();
-    let finishRenderTask = error => {
+    const finishRenderTask = error => {
      // The renderTask may have been replaced by a new one, so only remove
      // the reference to the renderTask if it matches the one that is
      // triggering this callback.
@ -338,9 +338,9 @@ class PDFThumbnailView {
      }
    };
-    let ctx = this._getPageDrawContext();
+    const ctx = this._getPageDrawContext();
-    let drawViewport = this.viewport.clone({ scale: this.scale });
+    const drawViewport = this.viewport.clone({ scale: this.scale });
-    let renderContinueCallback = cont => {
+    const renderContinueCallback = cont => {
      if (!this.renderingQueue.isHighestPriority(this)) {
        this.renderingState = RenderingStates.PAUSED;
        this.resume = () => {
@ -352,11 +352,11 @@ class PDFThumbnailView {
      cont();
    };
-    let renderContext = {
+    const renderContext = {
      canvasContext: ctx,
      viewport: drawViewport,
    };
-    let renderTask = (this.renderTask = this.pdfPage.render(renderContext));
+    const renderTask = (this.renderTask = this.pdfPage.render(renderContext));
    renderTask.onContinue = renderContinueCallback;
    renderTask.promise.then(
@ -374,7 +374,7 @@ class PDFThumbnailView {
    if (this.renderingState !== RenderingStates.INITIAL) {
      return;
    }
-    let img = pageView.canvas;
+    const img = pageView.canvas;
    if (!img) {
      return;
    }
@ -384,8 +384,8 @@ class PDFThumbnailView {
    this.renderingState = RenderingStates.FINISHED;
-    let ctx = this._getPageDrawContext(true);
+    const ctx = this._getPageDrawContext(true);
-    let canvas = ctx.canvas;
+    const canvas = ctx.canvas;
    if (img.width <= 2 * canvas.width) {
      ctx.drawImage(
        img,
@ -405,8 +405,11 @@ class PDFThumbnailView {
    // drawImage does an awful job of rescaling the image, doing it gradually.
    let reducedWidth = canvas.width << MAX_NUM_SCALING_STEPS;
    let reducedHeight = canvas.height << MAX_NUM_SCALING_STEPS;
-    let reducedImage = TempImageFactory.getCanvas(reducedWidth, reducedHeight);
+    const reducedImage = TempImageFactory.getCanvas(
-    let reducedImageCtx = reducedImage.getContext("2d");
+      reducedWidth,
      reducedHeight
    );
    const reducedImageCtx = reducedImage.getContext("2d");
    while (reducedWidth > img.width || reducedHeight > img.height) {
      reducedWidth >>= 1;
--- a/web/pdf_thumbnail_viewer.js
+++ b/web/pdf_thumbnail_viewer.js
@ -12,7 +12,6 @@
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 /* eslint no-var: error, prefer-const: error */
 import {
  getVisibleElements,
--- a/web/preferences.js
+++ b/web/preferences.js
@ -12,7 +12,6 @@
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 /* eslint no-var: error, prefer-const: error */
 let defaultPreferences = null;
 function getDefaultPreferences() {
--- a/web/secondary_toolbar.js
+++ b/web/secondary_toolbar.js
@ -12,7 +12,6 @@
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 /* eslint no-var: error, prefer-const: error */
 import { SCROLLBAR_PADDING, ScrollMode, SpreadMode } from "./ui_utils";
 import { CursorTool } from "./pdf_cursor_tools";
--- a/web/text_layer_builder.js
+++ b/web/text_layer_builder.js
@ -12,7 +12,6 @@
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 /* eslint no-var: error, prefer-const: error */
 import { getGlobalEventBus } from "./ui_utils";
 import { renderTextLayer } from "pdfjs-lib";
--- a/web/toolbar.js
+++ b/web/toolbar.js
@ -12,7 +12,6 @@
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 /* eslint no-var: error, prefer-const: error */
 import {
  animationStarted,
--- a/web/ui_utils.js
+++ b/web/ui_utils.js
@ -12,7 +12,6 @@
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 /* eslint no-var: error, prefer-const: error */
 const CSS_UNITS = 96.0 / 72.0;
 const DEFAULT_SCALE_VALUE = "auto";
--- a/web/view_history.js
+++ b/web/view_history.js
@ -12,7 +12,6 @@
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 /* eslint no-var: error, prefer-const: error */
 const DEFAULT_VIEW_HISTORY_CACHE_SIZE = 20;
--- a/web/viewer.js
+++ b/web/viewer.js
@ -12,7 +12,6 @@
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 /* eslint no-var: error, prefer-const: error */
 "use strict";
--- a/web/viewer_compatibility.js
+++ b/web/viewer_compatibility.js
@ -12,7 +12,6 @@
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 /* eslint no-var: error, prefer-const: error */
 const compatibilityParams = Object.create(null);
 if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {