Add support for modern ECMAScript class features

With ESLint 8 we should now finally be able to start using modern `class` features, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes/Public_class_fields and https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes/Private_class_fields

However, while both ESLint and Acorn now support this, it unfortunately turns out that Escodegen (which we use during building) still lack the necessary support. Looking at https://github.com/estools/escodegen there's not been any updates since last year, and there's also open PRs adding support for these new `class` features.

To avoid blocking usage of these `class` features in the PDF.js code-base, in particular *private* fields/methods, this patch thus proposes that we (hopefully temporarily) switch to an `escodegen` fork that has the necessary support; please see https://www.npmjs.com/package/@javascript-obfuscator/escodegen

While I have no reason to doubt the security of the `escodegen` fork, this patch nonetheless pins the version number. Furthermore, I've also diffed the output of the two `.js`-files in this forked package against the original files without finding anything that looks immediately "dangerous".

.eslintrc

@@ -1,6 +1,6 @@
 {
   "parserOptions": {
-    "ecmaVersion": 2021,
+    "ecmaVersion": 2022,
     "sourceType": "module",
   },
 

README.md

@@ -24,8 +24,8 @@ Feel free to stop by our [Matrix room](https://chat.mozilla.org/#/room/#pdfjs:mo
 ### Online demo
 
 Please note that the "Modern browsers" version assumes native support for
-features such as e.g. `async`/`await`, `ReadableStream`, optional chaining, and
+features such as e.g. `async`/`await`, `ReadableStream`, optional chaining,
-nullish coalescing.
+nullish coalescing, and private `class` fields/methods.
 
 + Modern browsers: https://mozilla.github.io/pdf.js/web/viewer.html
 

external/builder/preprocessor2.js

@@ -1,14 +1,14 @@
 "use strict";
 
 const acorn = require("acorn");
-const escodegen = require("escodegen");
+const escodegen = require("@javascript-obfuscator/escodegen");
 const vm = require("vm");
 const fs = require("fs");
 const path = require("path");
 
 const PDFJS_PREPROCESSOR_NAME = "PDFJSDev";
 const ROOT_PREFIX = "$ROOT/";
-const ACORN_ECMA_VERSION = 2021;
+const ACORN_ECMA_VERSION = 2022;
 
 function isLiteral(obj, value) {
   return obj.type === "Literal" && obj.value === value;

external/dist/README.md

@@ -8,7 +8,8 @@ This is a pre-built version of the PDF.js source code. It is automatically
 generated by the build scripts.
 
 For usage with older browsers or environments, without support for modern
-features such as e.g. `async`/`await`, `ReadableStream`, optional chaining, and
+features such as e.g. `async`/`await`, `ReadableStream`, optional chaining,
-nullish coalescing; please see the `legacy` folder.
+nullish coalescing, and private `class` fields/methods; please see the `legacy`
+folder.
 
 See https://github.com/mozilla/pdf.js for learning and contributing.

gulpfile.js

@@ -1375,7 +1375,7 @@ gulp.task("jsdoc", function (done) {
 gulp.task("types", function (done) {
   console.log("### Generating TypeScript definitions using `tsc`");
   const args = [
-    "target ES2020",
+    "target ESNext",
     "allowJS",
     "declaration",
     `outDir ${TYPES_DIR}`,

package-lock.json

@@ -1774,6 +1774,25 @@
       "integrity": "sha512-wdppn25U8z/2yiaT6YGquE6X8sSv7hNMWSXYSSU1jGv/yd6XqjXgTDJ8KP4NgjTXfJ3GbRjeeb8RTV7a/VpM+w==",
       "dev": true
     },
+    "@javascript-obfuscator/escodegen": {
+      "version": "2.2.2",
+      "resolved": "https://registry.npmjs.org/@javascript-obfuscator/escodegen/-/escodegen-2.2.2.tgz",
+      "integrity": "sha512-0VoGJun/lpGEPv8J8R8fpwt1iAGyctUjHTQoYoCbKY2rcGc6d+NycrqSMo61vRXhZiTnHgud1UF8dOI7UAPdTw==",
+      "dev": true,
+      "requires": {
+        "@javascript-obfuscator/estraverse": "^5.3.0",
+        "esprima": "^4.0.1",
+        "esutils": "^2.0.2",
+        "optionator": "^0.8.1",
+        "source-map": "~0.6.1"
+      }
+    },
+    "@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
+    },
     "@mapbox/node-pre-gyp": {
       "version": "1.0.5",
       "resolved": "https://registry.npmjs.org/@mapbox/node-pre-gyp/-/node-pre-gyp-1.0.5.tgz",
@@ -4333,27 +4352,6 @@
       "integrity": "sha1-G2HAViGQqN/2rjuyzwIAyhMLhtQ=",
       "dev": true
     },
-    "escodegen": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/escodegen/-/escodegen-2.0.0.tgz",
-      "integrity": "sha512-mmHKys/C8BFUGI+MAWNcSYoORYLMdPzjrknd2Vc+bUsjN5bXcr8EhrNB+UTqfL1y3I9c4fw2ihgtMPQLBRiQxw==",
-      "dev": true,
-      "requires": {
-        "esprima": "^4.0.1",
-        "estraverse": "^5.2.0",
-        "esutils": "^2.0.2",
-        "optionator": "^0.8.1",
-        "source-map": "~0.6.1"
-      },
-      "dependencies": {
-        "estraverse": {
-          "version": "5.2.0",
-          "resolved": "https://registry.npmjs.org/estraverse/-/estraverse-5.2.0.tgz",
-          "integrity": "sha512-BxbNGGNm0RyRYvUdHpIwv9IWzeM9XClbOxwoATuFdOE7ZE6wHL+HQ5T8hoPM+zHvmKzzsEqhgy0GrQ5X13afiQ==",
-          "dev": true
-        }
-      }
-    },
     "eslint": {
       "version": "8.0.1",
       "resolved": "https://registry.npmjs.org/eslint/-/eslint-8.0.1.tgz",
@@ -6576,7 +6574,8 @@
         },
         "yargs-parser": {
           "version": "5.0.0",
-          "resolved": "",
+          "resolved": "https://registry.npmjs.org/yargs-parser/-/yargs-parser-5.0.0.tgz",
+          "integrity": "sha1-J17PDX/+Bcd+ZOfIbkzZS/DhIoo=",
           "dev": true,
           "requires": {
             "camelcase": "^3.0.0"

package.json

@@ -14,7 +14,7 @@
     "cross-env": "^7.0.3",
     "dommatrix": "^0.0.6",
     "es-module-shims": "^1.3.0",
-    "escodegen": "^2.0.0",
+    "@javascript-obfuscator/escodegen": "2.2.2",
     "eslint": "^8.0.1",
     "eslint-config-prettier": "^8.3.0",
     "eslint-plugin-fetch-options": "^0.0.5",

test/types/tsconfig.json

@@ -6,14 +6,14 @@
     "moduleResolution": "node",
     "emitDecoratorMetadata": true,
     "experimentalDecorators": true,
-    "target": "es5",
+    "target": "ESNext",
-    "module": "es2015",
+    "module": "ESNext",
     "baseUrl": "./",
     "strict": true,
     "types": [],
     "lib": [
-      "es2017",
+      "ESNext",
-      "dom"
+      "DOM"
     ],
     "paths": {
       "pdfjs-dist": ["../../build/typestest"],