Replace the webpack+acorn transform with a Babel plugin

This commit converts the pdfjsdev-loader transform into a Babel plugin,
to skip a AST->string->AST round-trip.

Before this commit, the webpack build process was:
1. Babel parses the code
2. Babel transforms the AST
3. Babel generates the code
4. Acorn parses the code
5. pdfjsdev-loader transforms the AST
6. @javascript-obfuscator/escodegen generates the code
7. Webpack parses the file
8. Webpack concatenates the files

After this commit, it is reduced to:
1. Babel parses the code
2. Babel transforms the AST
3. babel-plugin-pdfjs-preprocessor transforms the AST
4. Babel generates the code
5. Webpack parses the file
6. Webpack concatenates the files

This change improves the build time by ~25% (tested on MacBook Air M2):
- `gulp lib`: 3.4s to 2.6s
- `gulp dist`: 36s to 29s
- `gulp generic`: 5.5s to 4.0s
- `gulp mozcentral`: 4.7s to 3.2s

The new Babel plugin doesn't support the `saveComments` option of
pdfjsdev-loader, and it just always discards comments. Even though
pdfjsdev-loader supported multiple values for that option, it was
effectively ignored due to `acorn` dropping comments by default.

external/builder/babel-plugin-pdfjs-preprocessor.mjs

@@ -1,347 +1,241 @@
-import * as acorn from "acorn";
+import { types as t, transformSync } from "@babel/core";
-import escodegen from "@javascript-obfuscator/escodegen";
 import fs from "fs";
-import path from "path";
+import { join as joinPaths } from "path";
 import vm from "vm";
 
 const PDFJS_PREPROCESSOR_NAME = "PDFJSDev";
 const ROOT_PREFIX = "$ROOT/";
-const ACORN_ECMA_VERSION = 2022;
-
-function isLiteral(obj, value) {
-  return obj.type === "Literal" && obj.value === value;
-}
 
 function isPDFJSPreprocessor(obj) {
   return obj.type === "Identifier" && obj.name === PDFJS_PREPROCESSOR_NAME;
 }
 
-function evalWithDefines(code, defines, loc) {
+function evalWithDefines(code, defines) {
   if (!code || !code.trim()) {
     throw new Error("No JavaScript expression given");
   }
   return vm.runInNewContext(code, defines, { displayErrors: false });
 }
 
-function handlePreprocessorAction(ctx, actionName, args, loc) {
+function handlePreprocessorAction(ctx, actionName, args, path) {
   try {
-    let arg;
+    const arg = args[0];
     switch (actionName) {
       case "test":
-        arg = args[0];
+        if (!t.isStringLiteral(arg)) {
-        if (!arg || arg.type !== "Literal" || typeof arg.value !== "string") {
           throw new Error("No code for testing is given");
         }
-        const isTrue = !!evalWithDefines(arg.value, ctx.defines);
+        return !!evalWithDefines(arg.value, ctx.defines);
-        return { type: "Literal", value: isTrue, loc };
       case "eval":
-        arg = args[0];
+        if (!t.isStringLiteral(arg)) {
-        if (!arg || arg.type !== "Literal" || typeof arg.value !== "string") {
           throw new Error("No code for eval is given");
         }
         const result = evalWithDefines(arg.value, ctx.defines);
         if (
           typeof result === "boolean" ||
           typeof result === "string" ||
-          typeof result === "number"
+          typeof result === "number" ||
+          typeof result === "object"
         ) {
-          return { type: "Literal", value: result, loc };
+          return result;
-        }
-        if (typeof result === "object") {
-          const parsedObj = acorn.parse("(" + JSON.stringify(result) + ")", {
-            ecmaVersion: ACORN_ECMA_VERSION,
-          });
-          parsedObj.body[0].expression.loc = loc;
-          return parsedObj.body[0].expression;
         }
         break;
       case "json":
-        arg = args[0];
+        if (!t.isStringLiteral(arg)) {
-        if (!arg || arg.type !== "Literal" || typeof arg.value !== "string") {
           throw new Error("Path to JSON is not provided");
         }
         let jsonPath = arg.value;
-        if (jsonPath.indexOf(ROOT_PREFIX) === 0) {
+        if (jsonPath.startsWith(ROOT_PREFIX)) {
-          jsonPath = path.join(
+          jsonPath = joinPaths(
             ctx.rootPath,
             jsonPath.substring(ROOT_PREFIX.length)
           );
         }
-        const jsonContent = fs.readFileSync(jsonPath).toString();
+        return JSON.parse(fs.readFileSync(jsonPath, "utf8"));
-        const parsedJSON = acorn.parse("(" + jsonContent + ")", {
-          ecmaVersion: ACORN_ECMA_VERSION,
-        });
-        parsedJSON.body[0].expression.loc = loc;
-        return parsedJSON.body[0].expression;
     }
     throw new Error("Unsupported action");
   } catch (e) {
-    throw new Error(
+    throw path.buildCodeFrameError(
       "Could not process " +
         PDFJS_PREPROCESSOR_NAME +
         "." +
         actionName +
-        " at " +
-        JSON.stringify(loc) +
-        "\n" +
-        e.name +
         ": " +
         e.message
     );
   }
 }
 
-function postprocessNode(ctx, node) {
+function babelPluginPDFJSPreprocessor(babel, ctx) {
-  switch (node.type) {
+  return {
-    case "ExportNamedDeclaration":
+    name: "babel-plugin-pdfjs-preprocessor",
-    case "ImportDeclaration":
+    manipulateOptions({ parserOpts }) {
-      if (
+      parserOpts.attachComment = false;
-        node.source &&
+    },
-        node.source.type === "Literal" &&
+    visitor: {
-        ctx.map &&
+      "ExportNamedDeclaration|ImportDeclaration": ({ node }) => {
-        ctx.map[node.source.value]
+        if (node.source && ctx.map?.[node.source.value]) {
-      ) {
+          node.source.value = ctx.map[node.source.value];
-        const newValue = ctx.map[node.source.value];
+        }
-        node.source.value = node.source.raw = newValue;
+      },
-      }
+      "IfStatement|ConditionalExpression": {
-      break;
+        exit(path) {
-    case "IfStatement":
+          const { node } = path;
-      if (isLiteral(node.test, true)) {
+          if (t.isBooleanLiteral(node.test)) {
-        // if (true) stmt1; => stmt1
+            // if (true) stmt1; => stmt1
-        return node.consequent;
+            // if (false) stmt1; else stmt2; => stmt2
-      } else if (isLiteral(node.test, false)) {
+            path.replaceWith(
-        // if (false) stmt1; else stmt2; => stmt2
+              node.test.value === true
-        return node.alternate || { type: "EmptyStatement", loc: node.loc };
+                ? node.consequent
-      }
+                : node.alternate || t.emptyStatement()
-      break;
-    case "ConditionalExpression":
-      if (isLiteral(node.test, true)) {
-        // true ? stmt1 : stmt2 => stmt1
-        return node.consequent;
-      } else if (isLiteral(node.test, false)) {
-        // false ? stmt1 : stmt2 => stmt2
-        return node.alternate;
-      }
-      break;
-    case "UnaryExpression":
-      if (node.operator === "typeof" && isPDFJSPreprocessor(node.argument)) {
-        // typeof PDFJSDev => 'object'
-        return { type: "Literal", value: "object", loc: node.loc };
-      }
-      if (
-        node.operator === "!" &&
-        node.argument.type === "Literal" &&
-        typeof node.argument.value === "boolean"
-      ) {
-        // !true => false,  !false => true
-        return { type: "Literal", value: !node.argument.value, loc: node.loc };
-      }
-      break;
-    case "LogicalExpression":
-      switch (node.operator) {
-        case "&&":
-          if (isLiteral(node.left, true)) {
-            return node.right;
-          }
-          if (isLiteral(node.left, false)) {
-            return node.left;
-          }
-          break;
-        case "||":
-          if (isLiteral(node.left, true)) {
-            return node.left;
-          }
-          if (isLiteral(node.left, false)) {
-            return node.right;
-          }
-          break;
-      }
-      break;
-    case "BinaryExpression":
-      switch (node.operator) {
-        case "==":
-        case "===":
-        case "!=":
-        case "!==":
-          if (
-            node.left.type === "Literal" &&
-            node.right.type === "Literal" &&
-            typeof node.left.value === typeof node.right.value
-          ) {
-            // folding two literals == and != check
-            switch (typeof node.left.value) {
-              case "string":
-              case "boolean":
-              case "number":
-                const equal = node.left.value === node.right.value;
-                return {
-                  type: "Literal",
-                  value: (node.operator[0] === "=") === equal,
-                  loc: node.loc,
-                };
-            }
-          }
-          break;
-      }
-      break;
-    case "CallExpression":
-      if (
-        node.callee.type === "MemberExpression" &&
-        isPDFJSPreprocessor(node.callee.object) &&
-        node.callee.property.type === "Identifier"
-      ) {
-        // PDFJSDev.xxxx(arg1, arg2, ...) => transform
-        const action = node.callee.property.name;
-        return handlePreprocessorAction(ctx, action, node.arguments, node.loc);
-      }
-      // require('string')
-      if (
-        node.callee.type === "Identifier" &&
-        node.callee.name === "require" &&
-        node.arguments.length === 1 &&
-        node.arguments[0].type === "Literal" &&
-        ctx.map &&
-        ctx.map[node.arguments[0].value]
-      ) {
-        const requireName = node.arguments[0];
-        requireName.value = requireName.raw = ctx.map[requireName.value];
-      }
-      break;
-    case "BlockStatement":
-      let subExpressionIndex = 0;
-      while (subExpressionIndex < node.body.length) {
-        switch (node.body[subExpressionIndex].type) {
-          case "EmptyStatement":
-            // Removing empty statements from the blocks.
-            node.body.splice(subExpressionIndex, 1);
-            continue;
-          case "BlockStatement":
-            // Block statements inside a block are moved to the parent one.
-            const subChildren = node.body[subExpressionIndex].body;
-            Array.prototype.splice.apply(node.body, [
-              subExpressionIndex,
-              1,
-              ...subChildren,
-            ]);
-            subExpressionIndex += Math.max(subChildren.length - 1, 0);
-            continue;
-          case "ReturnStatement":
-          case "ThrowStatement":
-            // Removing dead code after return or throw.
-            node.body.splice(
-              subExpressionIndex + 1,
-              node.body.length - subExpressionIndex - 1
             );
-            break;
-        }
-        subExpressionIndex++;
-      }
-      break;
-    case "FunctionDeclaration":
-    case "FunctionExpression":
-      const block = node.body;
-      if (
-        block.body.length > 0 &&
-        block.body.at(-1).type === "ReturnStatement" &&
-        !block.body.at(-1).argument
-      ) {
-        // Function body ends with return without arg -- removing it.
-        block.body.pop();
-      }
-      break;
-  }
-  return node;
-}
-
-function fixComments(ctx, node) {
-  if (!ctx.saveComments) {
-    return;
-  }
-  // Fixes double comments in the escodegen output.
-  delete node.trailingComments;
-  // Removes ESLint and other service comments.
-  if (node.leadingComments) {
-    const CopyrightRegExp = /\bcopyright\b/i;
-    const BlockCommentRegExp = /^\s*(globals|eslint|falls through)\b/;
-    const LineCommentRegExp = /^\s*eslint\b/;
-
-    let i = 0;
-    while (i < node.leadingComments.length) {
-      const type = node.leadingComments[i].type;
-      const value = node.leadingComments[i].value;
-
-      if (ctx.saveComments === "copyright") {
-        // Remove all comments, except Copyright notices and License headers.
-        if (!(type === "Block" && CopyrightRegExp.test(value))) {
-          node.leadingComments.splice(i, 1);
-          continue;
-        }
-      } else if (
-        (type === "Block" && BlockCommentRegExp.test(value)) ||
-        (type === "Line" && LineCommentRegExp.test(value))
-      ) {
-        node.leadingComments.splice(i, 1);
-        continue;
-      }
-      i++;
-    }
-  }
-}
-
-function traverseTree(ctx, node) {
-  // generic node processing
-  for (const i in node) {
-    const child = node[i];
-    if (typeof child === "object" && child !== null && child.type) {
-      const result = traverseTree(ctx, child);
-      if (result !== child) {
-        node[i] = result;
-      }
-    } else if (Array.isArray(child)) {
-      child.forEach(function (childItem, index) {
-        if (
-          typeof childItem === "object" &&
-          childItem !== null &&
-          childItem.type
-        ) {
-          const result = traverseTree(ctx, childItem);
-          if (result !== childItem) {
-            child[index] = result;
           }
+        },
+      },
+      UnaryExpression(path) {
+        const { node } = path;
+        if (node.operator === "typeof" && isPDFJSPreprocessor(node.argument)) {
+          // typeof PDFJSDev => 'object'
+          path.replaceWith(t.stringLiteral("object"));
+          return;
         }
-      });
+        if (node.operator === "!" && t.isBooleanLiteral(node.argument)) {
-    }
+          // !true => false,  !false => true
-  }
+          path.replaceWith(t.booleanLiteral(!node.argument.value));
+        }
+      },
+      LogicalExpression: {
+        exit(path) {
+          const { node } = path;
+          if (!t.isBooleanLiteral(node.left)) {
+            return;
+          }
 
-  node = postprocessNode(ctx, node) || node;
+          switch (node.operator) {
+            case "&&":
+              // true && expr => expr
+              // false && expr => false
+              path.replaceWith(
+                node.left.value === true ? node.right : node.left
+              );
+              break;
+            case "||":
+              // true || expr => true
+              // false || expr => expr
+              path.replaceWith(
+                node.left.value === true ? node.left : node.right
+              );
+              break;
+          }
+        },
+      },
+      BinaryExpression: {
+        exit(path) {
+          const { node } = path;
+          switch (node.operator) {
+            case "==":
+            case "===":
+            case "!=":
+            case "!==":
+              if (t.isLiteral(node.left) && t.isLiteral(node.right)) {
+                // folding == and != check that can be statically evaluated
+                const { confident, value } = path.evaluate();
+                if (confident) {
+                  path.replaceWith(t.booleanLiteral(value));
+                }
+              }
+          }
+        },
+      },
+      CallExpression(path) {
+        const { node } = path;
+        if (
+          t.isMemberExpression(node.callee) &&
+          isPDFJSPreprocessor(node.callee.object) &&
+          t.isIdentifier(node.callee.property) &&
+          !node.callee.computed
+        ) {
+          // PDFJSDev.xxxx(arg1, arg2, ...) => transform
+          const action = node.callee.property.name;
+          const result = handlePreprocessorAction(
+            ctx,
+            action,
+            node.arguments,
+            path
+          );
+          path.replaceWith(t.inherits(t.valueToNode(result), path.node));
+        }
 
-  fixComments(ctx, node);
+        // require('string')
-  return node;
+        if (
-}
+          t.isIdentifier(node.callee, { name: "require" }) &&
+          node.arguments.length === 1 &&
+          t.isStringLiteral(node.arguments[0]) &&
+          ctx.map?.[node.arguments[0].value]
+        ) {
+          const requireName = node.arguments[0];
+          requireName.value = requireName.raw = ctx.map[requireName.value];
+        }
+      },
+      BlockStatement: {
+        // Visit node in post-order so that recursive flattening
+        // of blocks works correctly.
+        exit(path) {
+          const { node } = path;
 
-function preprocessPDFJSCode(ctx, code) {
+          let subExpressionIndex = 0;
-  const format = ctx.format || {
+          while (subExpressionIndex < node.body.length) {
-    indent: {
+            switch (node.body[subExpressionIndex].type) {
-      style: " ",
+              case "EmptyStatement":
+                // Removing empty statements from the blocks.
+                node.body.splice(subExpressionIndex, 1);
+                continue;
+              case "BlockStatement":
+                // Block statements inside a block are flattened
+                // into the parent one.
+                const subChildren = node.body[subExpressionIndex].body;
+                node.body.splice(subExpressionIndex, 1, ...subChildren);
+                subExpressionIndex += Math.max(subChildren.length - 1, 0);
+                continue;
+              case "ReturnStatement":
+              case "ThrowStatement":
+                // Removing dead code after return or throw.
+                node.body.splice(
+                  subExpressionIndex + 1,
+                  node.body.length - subExpressionIndex - 1
+                );
+                break;
+            }
+            subExpressionIndex++;
+          }
+        },
+      },
+      Function: {
+        exit(path) {
+          if (!t.isBlockStatement(path.node.body)) {
+            // Arrow function with expression body
+            return;
+          }
+
+          const { body } = path.node.body;
+          if (
+            body.length > 0 &&
+            t.isReturnStatement(body.at(-1), { argument: null })
+          ) {
+            // Function body ends with return without arg -- removing it.
+            body.pop();
+          }
+        },
+      },
     },
   };
-  const parseOptions = {
-    ecmaVersion: ACORN_ECMA_VERSION,
-    locations: true,
-    sourceFile: ctx.sourceFile,
-    sourceType: "module",
-  };
-  const codegenOptions = {
-    format,
-    parse(input) {
-      return acorn.parse(input, { ecmaVersion: ACORN_ECMA_VERSION });
-    },
-    sourceMap: ctx.sourceMap,
-    sourceMapWithCode: ctx.sourceMap,
-  };
-  const syntax = acorn.parse(code, parseOptions);
-  traverseTree(ctx, syntax);
-  return escodegen.generate(syntax, codegenOptions);
 }
 
-export { preprocessPDFJSCode };
+function preprocessPDFJSCode(ctx, content) {
+  return transformSync(content, {
+    configFile: false,
+    plugins: [[babelPluginPDFJSPreprocessor, ctx]],
+  }).code;
+}
+
+export { babelPluginPDFJSPreprocessor, preprocessPDFJSCode };

external/builder/fixtures_esprima/blocks-expected.js

@@ -1,10 +1,10 @@
 function test() {
- "test";
+  "test";
- "1";
+  "1";
- "2";
+  "2";
- "3";
+  "3";
- if ("test") {
+  if ("test") {
-  "5";
+    "5";
- }
+  }
- "4";
+  "4";
 }

external/builder/fixtures_esprima/comments-expected.js

@@ -1,17 +1,17 @@
 function f1() {
- "1";
+  "1";
- "2";
+  "2";
 }
 function f2() {
- "1";
+  "1";
- "2";
+  "2";
 }
 function f3() {
- if ("1") {
+  if ("1") {
-  "1";
+    "1";
- }
+  }
- "2";
+  "2";
- if ("3") {
+  if ("3") {
-  "4";
+    "4";
- }
+  }
 }

external/builder/fixtures_esprima/constants-expected.js

@@ -10,6 +10,6 @@ var i = true;
 var j = false;
 var k = false;
 var l = true;
-var m = '1' === true;
+var m = false;
 var n = false;
 var o = true;

external/builder/fixtures_esprima/deadcode-expected.js

@@ -1,13 +1,21 @@
-function f1() {
+function f1() {}
-}
 function f2() {
- return 1;
+  return 1;
 }
 function f3() {
- var i = 0;
+  var i = 0;
- throw "test";
+  throw "test";
 }
 function f4() {
- var i = 0;
+  var i = 0;
 }
-
+var obj = {
+  method1() {},
+  method2() {}
+};
+class C {
+  method1() {}
+  method2() {}
+}
+var arrow1 = () => {};
+var arrow2 = () => {};

external/builder/fixtures_esprima/deadcode.js

@@ -23,3 +23,15 @@ function f4() {
   var j = 0;
 }
 
+var obj = {
+  method1() { return; var i = 0; },
+  method2() { return; },
+};
+
+class C {
+  method1() { return; var i = 0; }
+  method2() { return; }
+}
+
+var arrow1 = () => { return; var i = 0; };
+var arrow2 = () => { return; };

external/builder/fixtures_esprima/evals-expected.js

@@ -3,11 +3,17 @@ var b = true;
 var c = true;
 var d = false;
 var e = true;
-var f = 'text';
+var f = "text";
 var g = {
- "obj": { "i": 1 },
+  obj: {
- "j": 2
+    i: 1
+  },
+  j: 2
+};
+var h = {
+  test: "test"
 };
-var h = { 'test': 'test' };
 var i = '0';
-var j = { "i": 1 };
+var j = {
+  i: 1
+};

external/builder/fixtures_esprima/evals.json

@@ -1 +1 @@
-{ 'test': 'test' }
+{ "test": "test" }

external/builder/fixtures_esprima/ifs-expected.js

@@ -1,17 +1,17 @@
 if ('test') {
- "1";
+  "1";
 }
 {
- "1";
+  "1";
 }
 {
- "1";
+  "1";
 }
 ;
 {
- "2";
+  "2";
 }
 ;
 if ('1') {
- "1";
+  "1";
 }

external/builder/fixtures_esprima/importalias-expected.js

@@ -1,7 +1,5 @@
-import { Test } from 'import-name';
+import { Test } from "import-name";
 import { Test2 } from './non-alias';
-export {
+export { Test3 } from "import-name";
- Test3
+var Imp = require("import-name");
-} from 'import-name';
-var Imp = require('import-name');
 var Imp2 = require('./non-alias');

external/builder/test-fixtures.mjs

@@ -42,6 +42,12 @@ files.forEach(function (expectationFilename) {
   if (out !== expectation) {
     errors++;
 
+    // Allow regenerating the expected output using
+    //   OVERWRITE=true node ./external/builder/test-fixtures.mjs
+    if (process.env.OVERWRITE) {
+      fs.writeFileSync(expectationFilename, out + "\n");
+    }
+
     console.log("Assertion failed for " + inFilename);
     console.log("--------------------------------------------------");
     console.log("EXPECTED:");

external/builder/test-fixtures_esprima.mjs

@@ -1,7 +1,7 @@
 import { fileURLToPath } from "url";
 import fs from "fs";
 import path from "path";
-import { preprocessPDFJSCode } from "./preprocessor2.mjs";
+import { preprocessPDFJSCode } from "./babel-plugin-pdfjs-preprocessor.mjs";
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
@@ -48,6 +48,12 @@ files.forEach(function (expectationFilename) {
   if (out !== expectation) {
     errors++;
 
+    // Allow regenerating the expected output using
+    //   OVERWRITE=true node ./external/builder/test-fixtures_esprima.mjs
+    if (process.env.OVERWRITE) {
+      fs.writeFileSync(expectationFilename, out + "\n");
+    }
+
     console.log("Assertion failed for " + inFilename);
     console.log("--------------------------------------------------");
     console.log("EXPECTED:");

external/webpack/pdfjsdev-loader.mjs

@@ -1,41 +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.
- */
-
-import path from "path";
-import { preprocessPDFJSCode } from "../builder/preprocessor2.mjs";
-
-export default function (source) {
-  // Options must be specified, ignoring request if not.
-  if (!this.query || typeof this.query !== "object") {
-    return source;
-  }
-  this.cacheable();
-
-  const filePath = this.resourcePath;
-  const context = this.rootContext;
-  const sourcePath = path.relative(context, filePath).split(path.sep).join("/");
-
-  const ctx = Object.create(this.query);
-  ctx.sourceMap = true;
-  ctx.sourceFile = sourcePath;
-
-  const callback = this.callback;
-  const sourceAndMap = preprocessPDFJSCode(ctx, source);
-  const map = sourceAndMap.map.toJSON();
-  // escodegen does not embed source -- setting map's sourcesContent.
-  map.sourcesContent = [source];
-  callback(null, sourceAndMap.code, map);
-  return undefined;
-}

gulpfile.mjs

@@ -14,6 +14,10 @@
  */
 /* eslint-env node */
 
+import {
+  babelPluginPDFJSPreprocessor,
+  preprocessPDFJSCode,
+} from "./external/builder/babel-plugin-pdfjs-preprocessor.mjs";
 import { exec, spawn, spawnSync } from "child_process";
 import autoprefixer from "autoprefixer";
 import babel from "@babel/core";
@@ -30,7 +34,6 @@ import postcssDirPseudoClass from "postcss-dir-pseudo-class";
 import postcssDiscardComments from "postcss-discard-comments";
 import postcssNesting from "postcss-nesting";
 import { preprocess } from "./external/builder/builder.mjs";
-import { preprocessPDFJSCode } from "./external/builder/preprocessor2.mjs";
 import rename from "gulp-rename";
 import replace from "gulp-replace";
 import rimraf from "rimraf";
@@ -209,10 +212,11 @@ function createWebpackConfig(
   const isModule = output.library?.type === "module";
   const skipBabel = bundleDefines.SKIP_BABEL;
 
-  // `core-js`, see https://github.com/zloirock/core-js/issues/514,
+  const babelExcludeRegExp = [
-  // should be excluded from processing.
+    // `core-js`, see https://github.com/zloirock/core-js/issues/514,
-  const babelExcludes = ["node_modules[\\\\\\/]core-js"];
+    // should be excluded from processing.
-  const babelExcludeRegExp = new RegExp(`(${babelExcludes.join("|")})`);
+    /node_modules[\\/]core-js/,
+  ];
 
   const babelPresets = skipBabel
     ? undefined
@@ -227,7 +231,15 @@ function createWebpackConfig(
           },
         ],
       ];
-  const babelPlugins = [];
+  const babelPlugins = [
+    [
+      babelPluginPDFJSPreprocessor,
+      {
+        rootPath: __dirname,
+        defines: bundleDefines,
+      },
+    ],
+  ];
 
   const plugins = [];
   if (!disableLicenseHeader) {
@@ -335,14 +347,6 @@ function createWebpackConfig(
             targets: BABEL_TARGETS,
           },
         },
-        {
-          loader: path.join(__dirname, "external/webpack/pdfjsdev-loader.mjs"),
-          options: {
-            rootPath: __dirname,
-            saveComments: false,
-            defines: bundleDefines,
-          },
-        },
       ],
     },
     // Avoid shadowing actual Node.js variables with polyfills, by disabling
@@ -463,7 +467,6 @@ function createSandboxExternal(defines) {
   const licenseHeader = fs.readFileSync("./src/license_header.js").toString();
 
   const ctx = {
-    saveComments: false,
     defines,
   };
   return gulp
@@ -1572,13 +1575,15 @@ function buildLibHelper(bundleDefines, inputStream, outputDir) {
   }
   function preprocessLib(content) {
     const skipBabel = bundleDefines.SKIP_BABEL;
-    content = preprocessPDFJSCode(ctx, content);
     content = babel.transform(content, {
       sourceType: "module",
       presets: skipBabel
         ? undefined
         : [["@babel/preset-env", { loose: false, modules: false }]],
-      plugins: [babelPluginReplaceNonWebpackImport],
+      plugins: [
+        babelPluginReplaceNonWebpackImport,
+        [babelPluginPDFJSPreprocessor, ctx],
+      ],
       targets: BABEL_TARGETS,
     }).code;
     content = content.replaceAll(
@@ -1589,7 +1594,6 @@ function buildLibHelper(bundleDefines, inputStream, outputDir) {
   }
   const ctx = {
     rootPath: __dirname,
-    saveComments: false,
     defines: bundleDefines,
     map: {
       "pdfjs-lib": "../pdf.js",

package-lock.json

@@ -13,9 +13,7 @@
         "@babel/runtime": "^7.23.8",
         "@fluent/bundle": "^0.18.0",
         "@fluent/dom": "^0.9.0",
-        "@javascript-obfuscator/escodegen": "2.3.0",
         "@jazzer.js/core": "^2.1.0",
-        "acorn": "^8.11.3",
         "autoprefixer": "^10.4.17",
         "babel-loader": "^9.1.3",
         "caniuse-lite": "^1.0.30001579",
@@ -2330,33 +2328,6 @@
         "node": ">=8"
       }
     },
-    "node_modules/@javascript-obfuscator/escodegen": {
-      "version": "2.3.0",
-      "resolved": "https://registry.npmjs.org/@javascript-obfuscator/escodegen/-/escodegen-2.3.0.tgz",
-      "integrity": "sha512-QVXwMIKqYMl3KwtTirYIA6gOCiJ0ZDtptXqAv/8KWLG9uQU2fZqTVy7a/A5RvcoZhbDoFfveTxuGxJ5ibzQtkw==",
-      "dev": true,
-      "dependencies": {
-        "@javascript-obfuscator/estraverse": "^5.3.0",
-        "esprima": "^4.0.1",
-        "esutils": "^2.0.2",
-        "optionator": "^0.8.1"
-      },
-      "engines": {
-        "node": ">=6.0"
-      },
-      "optionalDependencies": {
-        "source-map": "~0.6.1"
-      }
-    },
-    "node_modules/@javascript-obfuscator/estraverse": {
-      "version": "5.3.0",
-      "resolved": "https://registry.npmjs.org/@javascript-obfuscator/estraverse/-/estraverse-5.3.0.tgz",
-      "integrity": "sha512-SxIFtV5/wlXYS7G3zLVj7CddLolX8Bm/hr68fiyNL3MyG2k4FwF9B5Z5GTpVLhw2EELYNwyoYBvFlR4gGnQPdw==",
-      "dev": true,
-      "engines": {
-        "node": ">=4.0"
-      }
-    },
     "node_modules/@jazzer.js/bug-detectors": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/@jazzer.js/bug-detectors/-/bug-detectors-2.1.0.tgz",
@@ -9954,19 +9925,6 @@
         "node": ">= 0.10"
       }
     },
-    "node_modules/levn": {
-      "version": "0.3.0",
-      "resolved": "https://registry.npmjs.org/levn/-/levn-0.3.0.tgz",
-      "integrity": "sha1-OwmSTt+fCDwEkP3UwLxEIeBHZO4=",
-      "dev": true,
-      "dependencies": {
-        "prelude-ls": "~1.1.2",
-        "type-check": "~0.3.2"
-      },
-      "engines": {
-        "node": ">= 0.8.0"
-      }
-    },
     "node_modules/liftoff": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/liftoff/-/liftoff-3.1.0.tgz",
@@ -13347,6 +13305,7 @@
     },
     "node_modules/npm/node_modules/lodash._baseindexof": {
       "version": "3.1.0",
+      "dev": true,
       "inBundle": true,
       "license": "MIT"
     },
@@ -13362,16 +13321,19 @@
     },
     "node_modules/npm/node_modules/lodash._bindcallback": {
       "version": "3.0.1",
+      "dev": true,
       "inBundle": true,
       "license": "MIT"
     },
     "node_modules/npm/node_modules/lodash._cacheindexof": {
       "version": "3.0.2",
+      "dev": true,
       "inBundle": true,
       "license": "MIT"
     },
     "node_modules/npm/node_modules/lodash._createcache": {
       "version": "3.1.2",
+      "dev": true,
       "inBundle": true,
       "license": "MIT",
       "dependencies": {
@@ -13386,6 +13348,7 @@
     },
     "node_modules/npm/node_modules/lodash._getnative": {
       "version": "3.9.1",
+      "dev": true,
       "inBundle": true,
       "license": "MIT"
     },
@@ -13403,6 +13366,7 @@
     },
     "node_modules/npm/node_modules/lodash.restparam": {
       "version": "3.6.1",
+      "dev": true,
       "inBundle": true,
       "license": "MIT"
     },
@@ -15878,23 +15842,6 @@
       "integrity": "sha1-+M33eISCb+Tf+T46nMN7HkSAdC4=",
       "dev": true
     },
-    "node_modules/optionator": {
-      "version": "0.8.3",
-      "resolved": "https://registry.npmjs.org/optionator/-/optionator-0.8.3.tgz",
-      "integrity": "sha512-+IW9pACdk3XWmmTXG8m3upGUJst5XRGzxMRjXzAuJ1XnIFNvfhjjIuYkDvysnPQ7qzqVzLt78BCruntqRhWQbA==",
-      "dev": true,
-      "dependencies": {
-        "deep-is": "~0.1.3",
-        "fast-levenshtein": "~2.0.6",
-        "levn": "~0.3.0",
-        "prelude-ls": "~1.1.2",
-        "type-check": "~0.3.2",
-        "word-wrap": "~1.2.3"
-      },
-      "engines": {
-        "node": ">= 0.8.0"
-      }
-    },
     "node_modules/ordered-read-streams": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/ordered-read-streams/-/ordered-read-streams-1.0.1.tgz",
@@ -16665,15 +16612,6 @@
         "node": ">=6"
       }
     },
-    "node_modules/prelude-ls": {
-      "version": "1.1.2",
-      "resolved": "https://registry.npmjs.org/prelude-ls/-/prelude-ls-1.1.2.tgz",
-      "integrity": "sha1-IZMqVJ9eUv/ZqCf1cOBL5iqX2lQ=",
-      "dev": true,
-      "engines": {
-        "node": ">= 0.8.0"
-      }
-    },
     "node_modules/prettier": {
       "version": "3.2.4",
       "resolved": "https://registry.npmjs.org/prettier/-/prettier-3.2.4.tgz",
@@ -19913,18 +19851,6 @@
         "node": "*"
       }
     },
-    "node_modules/type-check": {
-      "version": "0.3.2",
-      "resolved": "https://registry.npmjs.org/type-check/-/type-check-0.3.2.tgz",
-      "integrity": "sha1-WITKtRLPHTVeP7eE8wgEsrUg23I=",
-      "dev": true,
-      "dependencies": {
-        "prelude-ls": "~1.1.2"
-      },
-      "engines": {
-        "node": ">= 0.8.0"
-      }
-    },
     "node_modules/type-fest": {
       "version": "0.8.1",
       "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.8.1.tgz",
@@ -20997,15 +20923,6 @@
         "node": ">=0.4.0"
       }
     },
-    "node_modules/word-wrap": {
-      "version": "1.2.4",
-      "resolved": "https://registry.npmjs.org/word-wrap/-/word-wrap-1.2.4.tgz",
-      "integrity": "sha512-2V81OA4ugVo5pRo46hAoD2ivUJx8jXmWXfUkY4KFNw0hEptvN0QfH3K4nHiwzGeKl5rFKedV48QVoqYavy4YpA==",
-      "dev": true,
-      "engines": {
-        "node": ">=0.10.0"
-      }
-    },
     "node_modules/wordwrap": {
       "version": "0.0.2",
       "resolved": "https://registry.npmjs.org/wordwrap/-/wordwrap-0.0.2.tgz",

package.json

@@ -7,9 +7,7 @@
     "@babel/runtime": "^7.23.8",
     "@fluent/bundle": "^0.18.0",
     "@fluent/dom": "^0.9.0",
-    "@javascript-obfuscator/escodegen": "2.3.0",
     "@jazzer.js/core": "^2.1.0",
-    "acorn": "^8.11.3",
     "autoprefixer": "^10.4.17",
     "babel-loader": "^9.1.3",
     "caniuse-lite": "^1.0.30001579",