feat!: replace hybrid CJS/ESM build with ESM-only

.github/workflows/lint-build-test.yml

@@ -220,7 +220,7 @@ jobs:
               echo "Building changed packages:"
               jq -r '"- " + (.references[].path | ltrimstr("./") | rtrimstr("/tsconfig.build.json"))' "$TSCONFIG"
               echo ""
-              yarn ts-bridge --project "$TSCONFIG" --verbose
+              yarn tsc --build --project "$TSCONFIG" --verbose
             else
               echo "No packages to build."
             fi

.yarnrc.yml

@@ -27,7 +27,6 @@ npmPreapprovedPackages:
   - "@metamask/*"
   - "@metamask-previews/*"
   - "@lavamoat/*"
-  - "@ts-bridge/*"
 
 plugins:
   - path: .yarn/plugins/@yarnpkg/plugin-allow-scripts.cjs

docs/processes/building.md

@@ -1,7 +1,5 @@
 # Building packages
 
-[`ts-bridge`](https://github.com/ts-bridge/ts-bridge) is used to build packages in both CommonJS- and ESM-compatible formats.
-
 Built files show up in the `dist/` directory in each package. These are the files which will ultimately be published to NPM.
 
 - Run `yarn build` to build all packages in the monorepo.

docs/processes/package-migration-process-guide.md

@@ -85,12 +85,12 @@ Find the release commit SHA with `git log --oneline merged-packages/<package-nam
 ### **[PR#8]** 3. Remove files and directories that will be replaced by files in the monorepo root directory
 
 - **Remove**: `.github/`, `.git*`, `scripts/`, `knip.config.ts`, `.yarn/`, `.yarnrc.yml`, `yarn.lock`, `.editorconfig`, `.eslint*`, `.prettier*`, `.nvm*`.
-- **Keep**: `src/`, `tests/`, `CHANGELOG.md`, `LICENSE`, `package.json`, `README.md`, `jest.config.js`, `tsconfig*.json`, `typedoc.json`
+- **Keep**: `src/`, `tests/`, `CHANGELOG.md`, `LICENSE`, `package.json`, `README.md`, `jest.config.cjs`, `tsconfig*.json`, `typedoc.json`
 - [Example PR](https://github.com/MetaMask/core/pull/1764)
 
 ### **[PR#9]** 4. Replace config files
 
-- Update `tsconfig*.json`, `typedoc.json`, `jest.config.js` to extend from the corresponding files in the root directory by copying the contents of these files from other non-root packages.
+- Update `tsconfig*.json`, `typedoc.json`, `jest.config.cjs` to extend from the corresponding files in the root directory by copying the contents of these files from other non-root packages.
 - Preserve TypeScript compiler flags and its compilation target.
 - Add tsconfig reference paths for non-root packages that are upstream dependencies of the migration target.
 - Preserve Jest coverage threshold values.

docs/processes/testing.md

@@ -4,7 +4,7 @@
 
 Please follow the [MetaMask unit testing guidelines](https://github.com/MetaMask/contributor-docs/blob/main/docs/testing/unit-testing.md) when writing tests.
 
-If you need to customize the behavior of Jest for a package, see `jest.config.js` within that package.
+If you need to customize the behavior of Jest for a package, see `jest.config.cjs` within that package.
 
 - Run `yarn workspace <workspaceName> run test` to run all tests for a package.
 - Run `yarn workspace <workspaceName> run jest --no-coverage <file>` to run a test file within the context of a package.

eslint-suppressions.json

@@ -144,7 +144,7 @@
       "count": 1
     }
   },
-  "packages/assets-controllers/jest.environment.js": {
+  "packages/assets-controllers/jest.environment.cjs": {
     "n/prefer-global/text-decoder": {
       "count": 1
     },
@@ -500,7 +500,7 @@
       "count": 25
     },
     "@typescript-eslint/prefer-nullish-coalescing": {
-      "count": 1
+      "count": 2
     },
     "no-negated-condition": {
       "count": 1
@@ -1859,9 +1859,6 @@
     "@typescript-eslint/explicit-function-return-type": {
       "count": 10
     },
-    "@typescript-eslint/naming-convention": {
-      "count": 1
-    },
     "@typescript-eslint/no-explicit-any": {
       "count": 4
     },

eslint.config.mjs

@@ -107,7 +107,7 @@ const config = createConfig([
     extends: [nodejs],
   },
   {
-    files: ['**/*.{js,cjs}'],
+    files: ['**/*.cjs'],
     languageOptions: {
       sourceType: 'script',
       ecmaVersion: 2020,
@@ -152,6 +152,10 @@ const config = createConfig([
       'jest/no-alias-methods': 'error',
       'jest/no-commented-out-tests': 'error',
       'jest/no-disabled-tests': 'error',
+
+      // `import { jest } from '@jest/globals'` is required in ESM test files
+      // and intentionally shadows the Jest-injected global.
+      '@typescript-eslint/no-shadow': ['error', { allow: ['jest'] }],
     },
     settings: {
       node: {
@@ -192,14 +196,14 @@ const config = createConfig([
     },
   },
   {
-    files: ['**/jest.environment.js'],
+    files: ['**/jest.environment.cjs'],
     rules: {
       // These files run under Node, and thus `require(...)` is expected.
       'n/global-require': 'off',
     },
   },
   {
-    files: ['**/*.mjs'],
+    files: ['**/*.js', '**/*.mjs'],
     languageOptions: {
       sourceType: 'module',
     },

jest.config.packages.js → jest.config.packages.cjs

@@ -94,6 +94,11 @@ module.exports = {
       '<rootDir>/../../node_modules/@metamask/$1',
     ],
     '^uuid$': require.resolve('uuid'),
+    // The sources import `lodash-es`, because `lodash` is CommonJS and its
+    // named exports cannot be imported from an ES module. The tests compile to
+    // CommonJS, where the reverse is true, so they are pointed back at
+    // `lodash`. The two have the same API.
+    '^lodash-es$': require.resolve('lodash'),
   },
 
   // An array of regexp pattern strings, matched against all module paths before considered 'visible' to the module loader
@@ -190,7 +195,22 @@ module.exports = {
   // testURL: "http://localhost",
 
   // A map from regular expressions to paths to transformers
-  // transform: undefined,
+  // The packages are ESM, but Jest runs the tests as CommonJS: Jest only
+  // treats TypeScript as ESM when the extension is listed in
+  // `extensionsToTreatAsEsm`, so overriding the module settings here compiles
+  // the sources to CommonJS for tests without affecting the published build.
+  transform: {
+    '^.+\\.tsx?$': [
+      'ts-jest',
+      {
+        tsconfig: {
+          module: 'CommonJS',
+          moduleResolution: 'Node',
+          verbatimModuleSyntax: false,
+        },
+      },
+    ],
+  },
 
   // An array of regexp pattern strings that are matched against all source file paths, matched files will skip transformation
   // transformIgnorePatterns: undefined

jest.config.scripts.js → jest.config.scripts.cjs

@@ -42,6 +42,15 @@ module.exports = {
 
   preset: 'ts-jest',
 
+  // Unlike the packages, the scripts use `import.meta`, which has no CommonJS
+  // equivalent, so their tests run as ESM. Jest only treats TypeScript as ESM
+  // when the extension is listed here.
+  extensionsToTreatAsEsm: ['.ts', '.mts'],
+
+  transform: {
+    '^.+\\.m?tsx?$': ['ts-jest', { useESM: true }],
+  },
+
   // "resetMocks" resets all mocks, including mocked modules, to jest.fn(),
   // between each test case.
   resetMocks: true,

knip.config.mts

@@ -7,7 +7,7 @@ const config: KnipConfig = {
         'scripts/**/*.{ts,js,sh}',
         'tests/**/*.ts',
         '*.config.{js,cjs,mjs,ts}',
-        '.prettierrc.js',
+        '.prettierrc.cjs',
       ],
       project: ['scripts/**/*.ts', 'tests/**/*.ts', '*.{js,cjs,mjs,ts}'],
       ignore: ['scripts/create-package/package-template/**'],
@@ -41,7 +41,7 @@ const config: KnipConfig = {
       ignoreDependencies: [
         '@metamask/controller-utils',
         '@metamask/keyring-internal-api',
-        'lodash',
+        'lodash-es',
       ],
     },
     'packages/analytics-data-regulation-controller': {
@@ -66,7 +66,7 @@ const config: KnipConfig = {
       ignoreDependencies: [
         '@metamask/gas-fee-controller',
         '@metamask/remote-feature-flag-controller',
-        'lodash',
+        'lodash-es',
         'nock',
       ],
     },
@@ -127,7 +127,7 @@ const config: KnipConfig = {
       ignoreDependencies: [
         '@metamask/base-controller',
         '@metamask/superstruct',
-        'lodash',
+        'lodash-es',
       ],
     },
     'packages/multichain-network-controller': {
@@ -183,10 +183,10 @@ const config: KnipConfig = {
       ignoreDependencies: ['cockatiel', 'nock'],
     },
     'packages/selected-network-controller': {
-      ignoreDependencies: ['immer', 'lodash', 'nock'],
+      ignoreDependencies: ['immer', 'lodash-es', 'nock'],
     },
     'packages/signature-controller': {
-      ignoreDependencies: ['lodash'],
+      ignoreDependencies: ['lodash-es'],
     },
     'packages/snap-account-service': {
       ignoreDependencies: [

package.json

@@ -12,11 +12,12 @@
     "packages/*"
   ],
   "files": [],
+  "type": "module",
   "scripts": {
-    "build": "yarn ts-bridge --project tsconfig.build.json --verbose",
+    "build": "yarn tsc --build tsconfig.build.json --verbose",
     "build:clean": "yarn build:only-clean && yarn build",
     "build:docs": "yarn workspaces foreach --all --no-private --parallel --interlaced --verbose run build:docs",
-    "build:only-clean": "rimraf -g 'packages/*/dist'",
+    "build:only-clean": "rimraf -g 'packages/*/dist' 'packages/*/tsconfig.build.tsbuildinfo'",
     "build:types": "tsc --build tsconfig.build.json --verbose",
     "changelog:merge": "tsx scripts/merge-changelog-conflicts.ts",
     "changelog:update": "yarn workspaces foreach --all --no-private --parallel --interlaced --verbose run changelog:update",
@@ -54,14 +55,15 @@
     "test": "yarn test:scripts --silent --collectCoverage=false --reporters=jest-silent-reporter && yarn test:scripts:shell && yarn test:packages",
     "test:clean": "yarn workspaces foreach --all --parallel --verbose run test:clean && yarn test",
     "test:packages": "yarn test:verbose --silent --collectCoverage=false --reporters=jest-silent-reporter",
-    "test:scripts": "NODE_OPTIONS=--experimental-vm-modules yarn jest --config ./jest.config.scripts.js --silent",
+    "test:scripts": "NODE_OPTIONS=--experimental-vm-modules yarn jest --config ./jest.config.scripts.cjs --silent",
     "test:scripts:shell": "node_modules/bats/bin/bats scripts/*.bats",
     "test:verbose": "yarn workspaces foreach --all --parallel --verbose run test:verbose",
     "workspaces:list-versions": "./scripts/list-workspace-versions.sh"
   },
   "devDependencies": {
     "@actions/core": "^3.0.1",
     "@actions/github": "^9.1.1",
+    "@jest/globals": "^30.4.1",
     "@lavamoat/allow-scripts": "^3.0.4",
     "@lavamoat/preinstall-always-fail": "^2.1.0",
     "@metamask/auto-changelog": "^6.1.0",
@@ -76,7 +78,6 @@
     "@metamask/network-controller": "^36.0.0",
     "@metamask/skills": "^0.1.0",
     "@metamask/utils": "^11.12.0",
-    "@ts-bridge/cli": "^0.6.4",
     "@types/jest": "^30.0.0",
     "@types/lodash": "^4.14.191",
     "@types/node": "^22.13.14",
@@ -111,6 +112,7 @@
     "rimraf": "^5.0.5",
     "semver": "^7.6.3",
     "simple-git-hooks": "^2.8.0",
+    "ts-jest": "^29.4.11",
     "tsx": "^4.20.5",
     "typescript": "~5.3.3",
     "typescript-eslint": "^8.48.0",

packages/account-tree-controller/CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- **BREAKING:** Drop CommonJS support ([#9536](https://github.com/MetaMask/core/pull/9536))
+  - This package is now ESM-only, but can still be used in CommonJS projects via `require(esm)` in modern Node.js versions (22+), or dynamic imports in older Node.js versions.
 - **BREAKING:** Bump minimum Node.js version to 22 ([#9976](https://github.com/MetaMask/core/pull/9976))
 
 ## [9.0.0]

packages/account-tree-controller/jest.config.js → packages/account-tree-controller/jest.config.cjs

@@ -6,7 +6,7 @@
 const merge = require('deepmerge');
 const path = require('path');
 
-const baseConfig = require('../../jest.config.packages');
+const baseConfig = require('../../jest.config.packages.cjs');
 
 const displayName = path.basename(__dirname);
 

packages/account-tree-controller/package.json

@@ -18,19 +18,12 @@
   "files": [
     "dist/"
   ],
+  "type": "module",
   "sideEffects": false,
-  "main": "./dist/index.cjs",
-  "types": "./dist/index.d.cts",
   "exports": {
     ".": {
-      "import": {
-        "types": "./dist/index.d.mts",
-        "default": "./dist/index.mjs"
-      },
-      "require": {
-        "types": "./dist/index.d.cts",
-        "default": "./dist/index.cjs"
-      }
+      "types": "./dist/index.d.ts",
+      "default": "./dist/index.js"
     },
     "./package.json": "./package.json"
   },
@@ -39,9 +32,11 @@
     "registry": "https://registry.npmjs.org/"
   },
   "scripts": {
-    "build": "ts-bridge --project tsconfig.build.json --verbose --clean --no-references",
-    "build:all": "ts-bridge --project tsconfig.build.json --verbose --clean",
+    "build": "tsc --project tsconfig.build.json",
+    "build:all": "tsc --build tsconfig.build.json --verbose",
+    "build:clean": "yarn build:only-clean && yarn build",
     "build:docs": "typedoc",
+    "build:only-clean": "rimraf './dist' './tsconfig.build.tsbuildinfo'",
     "changelog:update": "../../scripts/update-changelog.sh @metamask/account-tree-controller",
     "changelog:validate": "../../scripts/validate-changelog.sh @metamask/account-tree-controller",
     "lint:tsconfigs": "tsx ../../scripts/lint-tsconfigs/lint-tsconfigs.mts",
@@ -68,17 +63,17 @@
     "@metamask/superstruct": "^3.4.1",
     "@metamask/utils": "^11.12.0",
     "fast-deep-equal": "^3.1.3",
-    "lodash": "^4.17.21"
+    "lodash-es": "^4.17.21"
   },
   "devDependencies": {
     "@metamask/account-api": "^2.0.0",
     "@metamask/auto-changelog": "^6.1.0",
     "@metamask/eth-hd-keyring": "^15.0.0",
     "@metamask/providers": "^22.1.0",
-    "@ts-bridge/cli": "^0.6.4",
     "@types/jest": "^30.0.0",
     "deepmerge": "^4.2.2",
     "jest": "^30.4.2",
+    "rimraf": "^5.0.5",
     "ts-jest": "^29.4.11",
     "tsx": "^4.20.5",
     "typedoc": "^0.25.13",

packages/accounts-controller/CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- **BREAKING:** Drop CommonJS support ([#9536](https://github.com/MetaMask/core/pull/9536))
+  - This package is now ESM-only, but can still be used in CommonJS projects via `require(esm)` in modern Node.js versions (22+), or dynamic imports in older Node.js versions.
 - **BREAKING:** Bump minimum Node.js version to 22 ([#9976](https://github.com/MetaMask/core/pull/9976))
 - Bump `@metamask/utils` from `^11.11.0` to `^11.12.0` ([#10076](https://github.com/MetaMask/core/pull/10076))
 

packages/accounts-controller/jest.config.js → packages/accounts-controller/jest.config.cjs

@@ -6,7 +6,7 @@
 const merge = require('deepmerge');
 const path = require('path');
 
-const baseConfig = require('../../jest.config.packages');
+const baseConfig = require('../../jest.config.packages.cjs');
 
 const displayName = path.basename(__dirname);