Enable the arrow-body-style ESLint rule

This manually ignores some cases where the resulting auto-formatting would not, as far as I'm concerned, constitute a readability improvement or where we'd just end up with more overall indentation.

Please see https://eslint.org/docs/latest/rules/arrow-body-style

.eslintrc

@@ -242,6 +242,7 @@
     }],
 
     // ECMAScript 6
+    "arrow-body-style": ["error", "as-needed"],
     "constructor-super": "error",
     "no-class-assign": "error",
     "no-const-assign": "error",

src/core/annotation.js

@@ -79,6 +79,7 @@ class AnnotationFactory {
       // with "GoToE" actions, from throwing and thus breaking parsing:
       pdfManager.ensureCatalog("attachments"),
     ]).then(
+      // eslint-disable-next-line arrow-body-style
       ([acroForm, xfaDatasets, structTreeRoot, baseUrl, attachments]) => {
         return {
           pdfManager,
@@ -2133,11 +2134,8 @@ class WidgetAnnotation extends Annotation {
       value,
     };
 
-    const encoder = val => {
-      return isAscii(val)
-        ? val
-        : stringToUTF16String(val, /* bigEndian = */ true);
-    };
+    const encoder = val =>
+      isAscii(val) ? val : stringToUTF16String(val, /* bigEndian = */ true);
     dict.set("V", Array.isArray(value) ? value.map(encoder) : encoder(value));
     this.amendSavedDict(annotationStorage, dict);
 

src/core/catalog.js

@@ -893,14 +893,13 @@ class Catalog {
         case "PrintPageRange":
           // The number of elements must be even.
           if (Array.isArray(value) && value.length % 2 === 0) {
-            const isValid = value.every((page, i, arr) => {
-              return (
+            const isValid = value.every(
+              (page, i, arr) =>
                 Number.isInteger(page) &&
                 page > 0 &&
                 (i === 0 || page >= arr[i - 1]) &&
                 page <= this.numPages
-              );
-            });
+            );
             if (isValid) {
               prefValue = value;
             }

src/core/document.js

@@ -1577,6 +1577,7 @@ class PDFDocument {
     } else {
       promise = catalog.getPageDict(pageIndex);
     }
+    // eslint-disable-next-line arrow-body-style
     promise = promise.then(([pageDict, ref]) => {
       return new Page({
         pdfManager: this.pdfManager,

src/core/evaluator.js

@@ -1039,14 +1039,15 @@ class PartialEvaluator {
 
             return translated;
           })
-          .catch(reason => {
-            return new TranslatedFont({
-              loadedName: "g_font_error",
-              font: new ErrorFont(`Type3 font load error: ${reason}`),
-              dict: translated.font,
-              evaluatorOptions: this.options,
-            });
-          });
+          .catch(
+            reason =>
+              new TranslatedFont({
+                loadedName: "g_font_error",
+                font: new ErrorFont(`Type3 font load error: ${reason}`),
+                dict: translated.font,
+                evaluatorOptions: this.options,
+              })
+          );
       })
       .then(translated => {
         state.font = translated.font;
@@ -1129,6 +1130,7 @@ class PartialEvaluator {
         case "Font":
           isSimpleGState = false;
 
+          // eslint-disable-next-line arrow-body-style
           promise = promise.then(() => {
             return this.handleSetFont(
               resources,
@@ -1154,6 +1156,7 @@ class PartialEvaluator {
           if (value instanceof Dict) {
             isSimpleGState = false;
 
+            // eslint-disable-next-line arrow-body-style
             promise = promise.then(() => {
               return this.handleSMask(
                 value,
@@ -1214,6 +1217,7 @@ class PartialEvaluator {
     fallbackFontDict = null,
     cssFontInfo = null
   ) {
+    // eslint-disable-next-line arrow-body-style
     const errorFont = async () => {
       return new TranslatedFont({
         loadedName: "g_font_error",

src/core/xfa/utils.js

@@ -129,12 +129,10 @@ function getRelevant(data) {
   return data
     .trim()
     .split(/\s+/)
-    .map(e => {
-      return {
-        excluded: e[0] === "-",
-        viewname: e.substring(1),
-      };
-    });
+    .map(e => ({
+      excluded: e[0] === "-",
+      viewname: e.substring(1),
+    }));
 }
 
 function getColor(data, def = [0, 0, 0]) {

src/display/annotation_layer.js

@@ -1838,9 +1838,10 @@ class ChoiceWidgetAnnotationElement extends WidgetAnnotationElement {
 
     const getItems = event => {
       const options = event.target.options;
-      return Array.prototype.map.call(options, option => {
-        return { displayValue: option.textContent, exportValue: option.value };
-      });
+      return Array.prototype.map.call(options, option => ({
+        displayValue: option.textContent,
+        exportValue: option.value,
+      }));
     };
 
     if (this.enableScripting && this.hasJSActions) {

src/display/api.js

@@ -3013,14 +3013,12 @@ class WorkerTransport {
     }
     const promise = this.messageHandler
       .sendWithPromise(name, null)
-      .then(results => {
-        return {
-          info: results[0],
-          metadata: results[1] ? new Metadata(results[1]) : null,
-          contentDispositionFilename: this._fullReader?.filename ?? null,
-          contentLength: this._fullReader?.contentLength ?? null,
-        };
-      });
+      .then(results => ({
+        info: results[0],
+        metadata: results[1] ? new Metadata(results[1]) : null,
+        contentDispositionFilename: this._fullReader?.filename ?? null,
+        contentLength: this._fullReader?.contentLength ?? null,
+      }));
     this.#methodPromises.set(name, promise);
     return promise;
   }

src/display/canvas.js

@@ -2359,8 +2359,8 @@ class CanvasGraphics {
       const color = IR[1];
       const baseTransform = this.baseTransform || getCurrentTransform(this.ctx);
       const canvasGraphicsFactory = {
-        createCanvasGraphics: ctx => {
-          return new CanvasGraphics(
+        createCanvasGraphics: ctx =>
+          new CanvasGraphics(
             ctx,
             this.commonObjs,
             this.objs,
@@ -2370,8 +2370,7 @@ class CanvasGraphics {
               optionalContentConfig: this.optionalContentConfig,
               markedContentStack: this.markedContentStack,
             }
-          );
-        },
+          ),
       };
       pattern = new TilingPattern(
         IR,

src/display/display_utils.js

@@ -466,15 +466,13 @@ class DOMCMapReaderFactory extends BaseCMapReaderFactory {
     return fetchData(
       url,
       /* type = */ this.isCompressed ? "arraybuffer" : "text"
-    ).then(data => {
-      return {
-        cMapData:
-          data instanceof ArrayBuffer
-            ? new Uint8Array(data)
-            : stringToBytes(data),
-        compressionType,
-      };
-    });
+    ).then(data => ({
+      cMapData:
+        data instanceof ArrayBuffer
+          ? new Uint8Array(data)
+          : stringToBytes(data),
+      compressionType,
+    }));
   }
 }
 

src/display/editor/tools.js

@@ -606,15 +606,14 @@ class AnnotationEditorUIManager {
   static get _keyboardManager() {
     const proto = AnnotationEditorUIManager.prototype;
 
-    const arrowChecker = self => {
-      // If the focused element is an input, we don't want to handle the arrow.
-      // For example, sliders can be controlled with the arrow keys.
-      return (
-        self.#container.contains(document.activeElement) &&
-        document.activeElement.tagName !== "BUTTON" &&
-        self.hasSomethingToControl()
-      );
-    };
+    /**
+     * If the focused element is an input, we don't want to handle the arrow.
+     * For example, sliders can be controlled with the arrow keys.
+     */
+    const arrowChecker = self =>
+      self.#container.contains(document.activeElement) &&
+      document.activeElement.tagName !== "BUTTON" &&
+      self.hasSomethingToControl();
 
     const textInputChecker = (_self, { target: el }) => {
       if (el instanceof HTMLInputElement) {

src/display/node_utils.js

@@ -98,9 +98,7 @@ class NodeCMapReaderFactory extends BaseCMapReaderFactory {
    * @ignore
    */
   _fetchData(url, compressionType) {
-    return fetchData(url).then(data => {
-      return { cMapData: data, compressionType };
-    });
+    return fetchData(url).then(data => ({ cMapData: data, compressionType }));
   }
 }
 

src/shared/util.js

@@ -1039,9 +1039,9 @@ function normalizeUnicode(str) {
       /([\u00a0\u00b5\u037e\u0eb3\u2000-\u200a\u202f\u2126\ufb00-\ufb04\ufb06\ufb20-\ufb36\ufb38-\ufb3c\ufb3e\ufb40-\ufb41\ufb43-\ufb44\ufb46-\ufba1\ufba4-\ufba9\ufbae-\ufbb1\ufbd3-\ufbdc\ufbde-\ufbe7\ufbea-\ufbf8\ufbfc-\ufbfd\ufc00-\ufc5d\ufc64-\ufcf1\ufcf5-\ufd3d\ufd88\ufdf4\ufdfa-\ufdfb\ufe71\ufe77\ufe79\ufe7b\ufe7d]+)|(\ufb05+)/gu;
     NormalizationMap = new Map([["ſt", "ſt"]]);
   }
-  return str.replaceAll(NormalizeRegex, (_, p1, p2) => {
-    return p1 ? p1.normalize("NFKC") : NormalizationMap.get(p2);
-  });
+  return str.replaceAll(NormalizeRegex, (_, p1, p2) =>
+    p1 ? p1.normalize("NFKC") : NormalizationMap.get(p2)
+  );
 }
 
 function getUuid() {

test/driver.js

@@ -106,6 +106,7 @@ async function inlineImages(node, silentErrors = false) {
           }
           return response.blob();
         })
+        // eslint-disable-next-line arrow-body-style
         .then(blob => {
           return new Promise((resolve, reject) => {
             const reader = new FileReader();
@@ -117,6 +118,7 @@ async function inlineImages(node, silentErrors = false) {
             reader.readAsDataURL(blob);
           });
         })
+        // eslint-disable-next-line arrow-body-style
         .then(dataUrl => {
           return new Promise((resolve, reject) => {
             image.onload = resolve;

test/integration/highlight_editor_spec.mjs

@@ -38,8 +38,8 @@ const getXY = (page, selector) =>
     return `${bbox.x}::${bbox.y}`;
   }, selector);
 
-const getSpanRectFromText = (page, pageNumber, text) => {
-  return page.evaluate(
+const getSpanRectFromText = (page, pageNumber, text) =>
+  page.evaluate(
     (number, content) => {
       for (const el of document.querySelectorAll(
         `.page[data-page-number="${number}"] > .textLayer > span`
@@ -54,7 +54,6 @@ const getSpanRectFromText = (page, pageNumber, text) => {
     pageNumber,
     text
   );
-};
 
 describe("Highlight Editor", () => {
   describe("Editor must be removed without exception", () => {

test/integration/test_utils.mjs

@@ -265,9 +265,10 @@ async function serializeBitmapDimensions(page) {
     const { map } =
       window.PDFViewerApplication.pdfDocument.annotationStorage.serializable;
     return map
-      ? Array.from(map.values(), x => {
-          return { width: x.bitmap.width, height: x.bitmap.height };
-        })
+      ? Array.from(map.values(), x => ({
+          width: x.bitmap.width,
+          height: x.bitmap.height,
+        }))
       : [];
   });
 }

test/unit/api_spec.js

@@ -2689,9 +2689,7 @@ describe("api", function () {
 
       const viewPromises = [];
       for (let i = 0; i < numPages; i++) {
-        viewPromises[i] = pdfDoc.getPage(i + 1).then(pdfPage => {
-          return pdfPage.view;
-        });
+        viewPromises[i] = pdfDoc.getPage(i + 1).then(pdfPage => pdfPage.view);
       }
 
       const [page1, page2, page3] = await Promise.all(viewPromises);
@@ -3412,7 +3410,9 @@ Caron Broadcasting, Inc., an Ohio corporation (“Lessee”).`)
           })
         );
 
+        // eslint-disable-next-line arrow-body-style
         const result1 = loadingTask1.promise.then(pdfDoc => {
+          // eslint-disable-next-line arrow-body-style
           return pdfDoc.getPage(1).then(pdfPage => {
             return pdfPage.getOperatorList().then(opList => {
               expect(opList.fnArray.length).toBeGreaterThan(100);
@@ -3425,7 +3425,9 @@ Caron Broadcasting, Inc., an Ohio corporation (“Lessee”).`)
           });
         });
 
+        // eslint-disable-next-line arrow-body-style
         const result2 = loadingTask2.promise.then(pdfDoc => {
+          // eslint-disable-next-line arrow-body-style
           return pdfDoc.getPage(1).then(pdfPage => {
             return pdfPage.getOperatorList().then(opList => {
               expect(opList.fnArray.length).toEqual(0);

test/unit/scripting_spec.js

@@ -152,14 +152,12 @@ describe("Scripting", function () {
     });
 
     it("should get field using a path", async () => {
-      const base = value => {
-        return {
-          id: getId(),
-          value,
-          actions: {},
-          type: "text",
-        };
-      };
+      const base = value => ({
+        id: getId(),
+        value,
+        actions: {},
+        type: "text",
+      });
       const data = {
         objects: {
           A: [base(1)],

web/pdf_document_properties.js

@@ -129,6 +129,7 @@ class PDFDocumentProperties {
       this.#parseFileSize(contentLength),
       this.#parseDate(info.CreationDate),
       this.#parseDate(info.ModDate),
+      // eslint-disable-next-line arrow-body-style
       this.pdfDocument.getPage(currentPageNumber).then(pdfPage => {
         return this.#parsePageSize(getPageSizeInches(pdfPage), pagesRotation);
       }),

web/pdf_find_controller.js

@@ -842,12 +842,11 @@ class PDFFindController {
       const extractTextCapability = new PromiseCapability();
       this._extractTextPromises[i] = extractTextCapability.promise;
 
+      // eslint-disable-next-line arrow-body-style
       promise = promise.then(() => {
         return this._pdfDocument
           .getPage(i + 1)
-          .then(pdfPage => {
-            return pdfPage.getTextContent(textOptions);
-          })
+          .then(pdfPage => pdfPage.getTextContent(textOptions))
           .then(
             textContent => {
               const strBuf = [];