Remove SystemJS usage, in development mode, from the worker

Now that https://bugzilla.mozilla.org/show_bug.cgi?id=1247687 has landed in Firefox, we're able to use worker-modules during development :-)

This removes the final piece of SystemJS usage from the PDF.js library, thus allowing a fair bit of clean-up, and we now use *only* native `import`/`export` statements everywhere in development mode.

.eslintrc

@@ -28,7 +28,6 @@
   "globals": {
     "PDFJSDev": false,
     "exports": false,
-    "SystemJS": false,
   },
 
   "rules": {

external/systemjs/plugin-babel-cached.js

@@ -1,152 +0,0 @@
-/* Copyright 2017 Mozilla Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-/* eslint-disable no-var */
-
-var babel = require("plugin-babel");
-
-var cacheExpiration = 60 /* min */ * 60 * 1000;
-var dbVersion = 1;
-var dbName = "babelcache";
-var dbCacheTable = "translated";
-var dbPromise;
-
-function getDb() {
-  if (!dbPromise) {
-    dbPromise = new Promise(function (resolve, reject) {
-      var request = indexedDB.open(dbName, dbVersion);
-      request.onupgradeneeded = function () {
-        var db = request.result;
-        db.createObjectStore(dbCacheTable, { keyPath: "address" });
-      };
-      request.onsuccess = function () {
-        var db = request.result;
-        resolve(db);
-      };
-      request.onerror = function () {
-        console.warn("getDb: " + request.error);
-        reject(request.error);
-      };
-    });
-  }
-  return dbPromise;
-}
-
-function storeCache(address, hashCode, translated, format, sourceMap) {
-  return getDb().then(function (db) {
-    var tx = db.transaction(dbCacheTable, "readwrite");
-    var store = tx.objectStore(dbCacheTable);
-    store.put({
-      address,
-      hashCode,
-      translated,
-      expires: Date.now() + cacheExpiration,
-      format,
-      sourceMap,
-    });
-    return new Promise(function (resolve, reject) {
-      tx.oncomplete = function () {
-        resolve();
-      };
-      tx.onerror = function () {
-        resolve();
-      };
-    });
-  });
-}
-
-function loadCache(address, hashCode) {
-  return getDb().then(function (db) {
-    var tx = db.transaction(dbCacheTable, "readonly");
-    var store = tx.objectStore(dbCacheTable);
-    var getAddress = store.get(address);
-    return new Promise(function (resolve, reject) {
-      tx.oncomplete = function () {
-        var found = getAddress.result;
-        var isValid =
-          found && found.hashCode === hashCode && Date.now() < found.expires;
-        resolve(
-          isValid
-            ? {
-                translated: found.translated,
-                format: found.format,
-                sourceMap: found.sourceMap,
-              }
-            : null
-        );
-      };
-      tx.onerror = function () {
-        resolve(null);
-      };
-    });
-  });
-}
-
-var encoder = new TextEncoder("utf-8");
-function sha256(str) {
-  var buffer = encoder.encode(str);
-  return crypto.subtle.digest("SHA-256", buffer).then(function (hash) {
-    var data = new Int32Array(hash);
-    return (
-      data[0].toString(36) +
-      "-" +
-      data[1].toString(36) +
-      "-" +
-      data[2].toString(36) +
-      "-" +
-      data[3].toString(36)
-    );
-  });
-}
-
-exports.translate = function (load, opt) {
-  var savedHashCode, babelTranslateError;
-  return sha256(load.source)
-    .then(function (hashCode) {
-      savedHashCode = hashCode;
-      return loadCache(load.address, hashCode);
-    })
-    .then(
-      function (cache) {
-        if (cache) {
-          load.metadata.format = cache.format;
-          return cache.translated;
-        }
-        return babel.translate.call(this, load, opt).then(
-          function (translated) {
-            return storeCache(
-              load.address,
-              savedHashCode,
-              translated,
-              load.metadata.format,
-              load.metadata.sourceMap
-            ).then(function () {
-              return translated;
-            });
-          },
-          function (reason) {
-            throw (babelTranslateError = reason);
-          }
-        );
-      }.bind(this)
-    )
-    .catch(
-      function (reason) {
-        if (babelTranslateError) {
-          throw babelTranslateError;
-        }
-        return babel.translate.call(this, load, opt);
-      }.bind(this)
-    );
-};

package-lock.json

@@ -55,8 +55,6 @@
         "streamqueue": "^1.1.2",
         "stylelint": "^15.6.0",
         "stylelint-prettier": "^3.0.0",
-        "systemjs": "^0.21.6",
-        "systemjs-plugin-babel": "^0.0.25",
         "terser": "^5.17.1",
         "through2": "^4.0.2",
         "ttest": "^4.0.0",
@@ -17482,18 +17480,6 @@
       "integrity": "sha1-WPcc7jvVGbWdSyqEO2x95krAR2Q=",
       "dev": true
     },
-    "node_modules/systemjs": {
-      "version": "0.21.6",
-      "resolved": "https://registry.npmjs.org/systemjs/-/systemjs-0.21.6.tgz",
-      "integrity": "sha512-R+5S9eV9vcQgWOoS4D87joZ4xkFJHb19ZsyKY07D1+VBDE9bwYcU+KXE0r5XlDA8mFoJGyuWDbfrNoh90JsA8g==",
-      "dev": true
-    },
-    "node_modules/systemjs-plugin-babel": {
-      "version": "0.0.25",
-      "resolved": "https://registry.npmjs.org/systemjs-plugin-babel/-/systemjs-plugin-babel-0.0.25.tgz",
-      "integrity": "sha512-RMKSizWWlw4+IpDB385ugxn7Owd9W+HEtjYDQ6yO1FpsnER/vk6FbXRweUF+mvRi6EHgk8vDdUdtui7ReDwX3w==",
-      "dev": true
-    },
     "node_modules/table": {
       "version": "6.8.1",
       "resolved": "https://registry.npmjs.org/table/-/table-6.8.1.tgz",
@@ -32651,18 +32637,6 @@
       "integrity": "sha1-WPcc7jvVGbWdSyqEO2x95krAR2Q=",
       "dev": true
     },
-    "systemjs": {
-      "version": "0.21.6",
-      "resolved": "https://registry.npmjs.org/systemjs/-/systemjs-0.21.6.tgz",
-      "integrity": "sha512-R+5S9eV9vcQgWOoS4D87joZ4xkFJHb19ZsyKY07D1+VBDE9bwYcU+KXE0r5XlDA8mFoJGyuWDbfrNoh90JsA8g==",
-      "dev": true
-    },
-    "systemjs-plugin-babel": {
-      "version": "0.0.25",
-      "resolved": "https://registry.npmjs.org/systemjs-plugin-babel/-/systemjs-plugin-babel-0.0.25.tgz",
-      "integrity": "sha512-RMKSizWWlw4+IpDB385ugxn7Owd9W+HEtjYDQ6yO1FpsnER/vk6FbXRweUF+mvRi6EHgk8vDdUdtui7ReDwX3w==",
-      "dev": true
-    },
     "table": {
       "version": "6.8.1",
       "resolved": "https://registry.npmjs.org/table/-/table-6.8.1.tgz",

package.json

@@ -48,8 +48,6 @@
     "streamqueue": "^1.1.2",
     "stylelint": "^15.6.0",
     "stylelint-prettier": "^3.0.0",
-    "systemjs": "^0.21.6",
-    "systemjs-plugin-babel": "^0.0.25",
     "terser": "^5.17.1",
     "through2": "^4.0.2",
     "ttest": "^4.0.0",

src/core/.eslintrc

@@ -1,13 +0,0 @@
-{
-  "parserOptions": {
-    "ecmaVersion": 2017,
-  },
-
-  "extends": [
-    "../../.eslintrc"
-  ],
-
-  "env": {
-    "es2017": true,
-  },
-}

src/core/unicode.js

@@ -12,7 +12,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-/* no-babel-preset */
 
 import { getLookupTableFactory } from "./core_utils.js";
 

src/display/api.js

@@ -2130,12 +2130,9 @@ class PDFWorker {
           );
         }
 
-        // Some versions of FF can't create a worker on localhost, see:
-        // https://bugzilla.mozilla.org/show_bug.cgi?id=683280
         const worker =
           typeof PDFJSDev === "undefined" &&
-          !workerSrc.endsWith("/build/pdf.worker.js") &&
+          !workerSrc.endsWith("/build/pdf.worker.js")
-          !workerSrc.endsWith("/src/worker_loader.js")
             ? new Worker(workerSrc, { type: "module" })
             : new Worker(workerSrc);
         const messageHandler = new MessageHandler("main", "worker", worker);

src/shared/.eslintrc

@@ -1,13 +0,0 @@
-{
-  "parserOptions": {
-    "ecmaVersion": 2017,
-  },
-
-  "extends": [
-    "../../.eslintrc"
-  ],
-
-  "env": {
-    "es2017": true,
-  },
-}

src/worker_loader.js

@@ -1,32 +0,0 @@
-/* Copyright 2012 Mozilla Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-"use strict";
-
-// Patch importScripts to work around a bug in WebKit and Chrome 48-.
-// See https://crbug.com/572225 and https://webkit.org/b/153317.
-self.importScripts = (function (importScripts) {
-  return function () {
-    setTimeout(function () {}, 0);
-    return importScripts.apply(this, arguments);
-  };
-})(importScripts);
-
-importScripts("../node_modules/systemjs/dist/system.js");
-importScripts("../systemjs.config.js");
-
-SystemJS.import("pdfjs/core/worker.js").then(function () {
-  // Worker is loaded at this point.
-});

systemjs.config.js

@@ -1,96 +0,0 @@
-/* Copyright 2017 Mozilla Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-/* eslint-disable no-var, unicorn/no-typeof-undefined */
-
-"use strict";
-
-(function () {
-  var baseLocation;
-  if (typeof document !== "undefined") {
-    baseLocation = new URL("./", document.currentScript.src);
-  } else if (typeof location !== "undefined") {
-    // Probably worker -- walking subfolders until we will reach root.
-    baseLocation = location;
-    while (baseLocation.href.includes("/src/")) {
-      baseLocation = new URL("..", baseLocation);
-    }
-  } else {
-    throw new Error("Cannot configure SystemJS");
-  }
-
-  var PluginBabelPath = "node_modules/systemjs-plugin-babel/plugin-babel.js";
-  var SystemJSPluginBabelPath =
-    "node_modules/systemjs-plugin-babel/systemjs-babel-browser.js";
-  var PluginBabelCachePath = "external/systemjs/plugin-babel-cached.js";
-
-  var isCachingPossible =
-    typeof indexedDB !== "undefined" &&
-    typeof TextEncoder !== "undefined" &&
-    typeof crypto !== "undefined" &&
-    typeof crypto.subtle !== "undefined";
-
-  // When we create a bundle, webpack is run on the source and it will replace
-  // require with __webpack_require__. When we want to use the real require,
-  // __non_webpack_require__ has to be used.
-  // In this target, we don't create a bundle, so we have to replace the
-  // occurrences of __non_webpack_require__ ourselves.
-  function babelPluginReplaceNonWebPackRequire(babel) {
-    return {
-      visitor: {
-        Identifier(path, state) {
-          if (path.node.name === "__non_webpack_require__") {
-            path.replaceWith(babel.types.identifier("require"));
-          }
-        },
-      },
-    };
-  }
-
-  SystemJS.config({
-    packages: {
-      "": {
-        defaultExtension: "js",
-      },
-    },
-    paths: {
-      pdfjs: new URL("src", baseLocation).href,
-      "pdfjs-web": new URL("web", baseLocation).href,
-      "pdfjs-test": new URL("test", baseLocation).href,
-      "pdfjs-lib": new URL("src/pdf", baseLocation).href,
-      "core-js": new URL("node_modules/core-js", baseLocation).href,
-      "web-streams-polyfill": new URL(
-        "node_modules/web-streams-polyfill",
-        baseLocation
-      ).href,
-    },
-    meta: {
-      "*": {
-        scriptLoad: false,
-        esModule: true,
-        babelOptions: {
-          env: false,
-          plugins: [babelPluginReplaceNonWebPackRequire],
-        },
-      },
-    },
-    map: {
-      "plugin-babel": new URL(PluginBabelPath, baseLocation).href,
-      "systemjs-babel-build": new URL(SystemJSPluginBabelPath, baseLocation)
-        .href,
-      "plugin-babel-cached": new URL(PluginBabelCachePath, baseLocation).href,
-    },
-    transpiler: isCachingPossible ? "plugin-babel-cached" : "plugin-babel",
-  });
-})();

web/app.js

@@ -309,12 +309,7 @@ const PDFViewerApplication = {
     const { mainContainer, viewerContainer } = this.appConfig,
       params = parseQueryString(hash);
 
-    if (
+    if (params.get("disableworker") === "true") {
-      typeof PDFJSDev === "undefined" &&
-      params.get("workermodules") === "true"
-    ) {
-      AppOptions.set("workerSrc", "../src/pdf.worker.js");
-    } else if (params.get("disableworker") === "true") {
       try {
         await loadFakeWorker();
       } catch (ex) {

web/app_options.js

@@ -292,7 +292,7 @@ const defaultOptions = {
     value:
       // eslint-disable-next-line no-nested-ternary
       typeof PDFJSDev === "undefined"
-        ? "../src/worker_loader.js"
+        ? "../src/pdf.worker.js"
         : PDFJSDev.test("MOZCENTRAL")
         ? "resource://pdf.js/build/pdf.worker.js"
         : "../build/pdf.worker.js",