perf: transpile js to es6 (#3699)

js-packages/webpack-config/.yarnrc.yml

@@ -1 +0,0 @@
-yarnPath: .yarn/releases/yarn-3.1.0.cjs

js-packages/webpack-config/babel.config.js

@@ -1,19 +1,36 @@
 module.exports = {
+  assumptions: {
+    // Defines assumptions Babel can make about our
+    // code to better optimise it.
+    //
+    // These are rarely used features that are generally
+    // considered very bad practice anyway.
+    //
+    // See: https://babeljs.io/docs/en/assumptions
+    constantSuper: true,
+    ignoreFunctionLength: true,
+    noDocumentAll: true,
+    noNewArrows: true,
+    privateFieldsAsProperties: true,
+  },
+  targets: {
+    // `not android > 0` means the build-in Android browser used up to Android 4.4 KitKat.
+    browsers: '>0.2%, not dead, not android > 0, not operamini all',
+  },
   presets: [
     require.resolve('@babel/preset-react'),
     require.resolve('@babel/preset-typescript'),
     [
       require.resolve('@babel/preset-env'),
       {
-        modules: false,
-        loose: true,
+        modules: 'auto',
       },
     ],
   ],
   plugins: [
     [require.resolve('@babel/plugin-transform-runtime'), { useESModules: true }],
-    [require.resolve('@babel/plugin-proposal-class-properties'), { loose: true }],
-    [require.resolve('@babel/plugin-proposal-private-methods'), { loose: true }],
+    [require.resolve('@babel/plugin-proposal-class-properties')],
+    [require.resolve('@babel/plugin-proposal-private-methods')],
     [
       require.resolve('@babel/plugin-transform-react-jsx'),
       {

js-packages/webpack-config/index.js

@@ -38,7 +38,7 @@ const plugins = [];
  * is required at build-time from an extension/core's scope) are redirected to the
  * copy of `@babel/runtime` which is a dependency of this package.
  *
- * This removes the need for hoisting, and allows for Plyug'n'Play compatibility.
+ * This removes the need for hoisting, and allows for Plug'n'Play compatibility.
  *
  * Thanks goes to Yarn's lead maintainer @arcanis for helping me get to this
  * solution.

js-packages/webpack-config/package.json

@@ -5,27 +5,31 @@
   "main": "index.js",
   "author": "Flarum Team",
   "license": "MIT",
+  "prettier": "@flarum/prettier-config",
   "peerDependencies": {
     "webpack": "^5.76.0"
   },
   "dependencies": {
-    "@babel/core": "^7.16.0",
-    "@babel/plugin-proposal-class-properties": "^7.16.0",
-    "@babel/plugin-proposal-private-methods": "^7.16.0",
-    "@babel/plugin-transform-object-assign": "^7.16.0",
-    "@babel/plugin-transform-react-jsx": "^7.16.0",
-    "@babel/plugin-transform-runtime": "^7.16.0",
-    "@babel/preset-env": "^7.16.0",
-    "@babel/preset-react": "^7.16.0",
-    "@babel/preset-typescript": "^7.16.0",
-    "@babel/runtime": "^7.16.0",
-    "babel-loader": "^8.2.3",
-    "typescript": "^4.4.4",
+    "@babel/core": "^7.20.2",
+    "@babel/plugin-proposal-class-properties": "^7.18.6",
+    "@babel/plugin-proposal-private-methods": "^7.18.6",
+    "@babel/plugin-transform-object-assign": "^7.18.6",
+    "@babel/plugin-transform-react-jsx": "^7.19.0",
+    "@babel/plugin-transform-runtime": "^7.19.6",
+    "@babel/preset-env": "^7.20.2",
+    "@babel/preset-react": "^7.18.6",
+    "@babel/preset-typescript": "^7.18.6",
+    "@babel/runtime": "^7.20.1",
+    "babel-loader": "^9.1.0",
+    "typescript": "^4.9.3",
     "webpack": "^5.76.0",
-    "webpack-bundle-analyzer": "^4.5.0"
+    "webpack-bundle-analyzer": "^4.7.0"
   },
   "devDependencies": {
-    "prettier": "^2.4.1"
+    "prettier": "^2.8.0",
+    "@flarum/prettier-config": "^1.0.0"
   },
-  "packageManager": "yarn@3.1.0"
+  "scripts": {
+    "format": "prettier --write ."
+  }
 }