Build package as both CJS and ESM

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

@@ -17,8 +17,8 @@ jobs:
       - name: Install Yarn dependencies
         run: yarn --immutable
 
-  build:
-    name: Build
+  build-source:
+    name: Build source
     runs-on: ubuntu-latest
     needs:
       - prepare
@@ -33,7 +33,32 @@ jobs:
           node-version: ${{ matrix.node-version }}
           cache: 'yarn'
       - run: yarn --immutable --immutable-cache
-      - run: yarn build
+      - run: yarn build:source
+      - name: Require clean working directory
+        shell: bash
+        run: |
+          if ! git diff --exit-code; then
+            echo "Working tree dirty at end of job"
+            exit 1
+          fi
+
+  build-types:
+    name: Build types
+    runs-on: ubuntu-latest
+    needs:
+      - prepare
+    strategy:
+      matrix:
+        node-version: [16.x, 18.x, 20.x]
+    steps:
+      - uses: actions/checkout@v3
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: 'yarn'
+      - run: yarn --immutable --immutable-cache
+      - run: yarn build:types
       - name: Require clean working directory
         shell: bash
         run: |

.swcrc.build.json

@@ -0,0 +1,18 @@
+{
+  "$schema": "https://json.schemastore.org/swcrc",
+  "jsc": {
+    "parser": {
+      "syntax": "typescript"
+    },
+    "target": "es2020"
+  },
+  "sourceMaps": true,
+  "exclude": [
+    ".*__fixtures__.*",
+    ".*__mocks__.*",
+    ".*__snapshots__.*",
+    ".*__tests?__.*",
+    ".*\\.test\\.?.*\\.tsx?",
+    ".*\\.d\\.tsx?"
+  ]
+}

constraints.pro

@@ -65,15 +65,18 @@ gen_enforced_field(WorkspaceCwd, 'repository.url', 'https://github.com/MetaMask/
 % The license for the package must be specified.
 gen_enforced_field(WorkspaceCwd, 'license').
 
-% The entrypoint for the package must be `./dist/index.js`.
-gen_enforced_field(WorkspaceCwd, 'main', './dist/index.js').
+% The type definitions entrypoint the package must be `./dist/types/index.d.ts`.
+gen_enforced_field(WorkspaceCwd, 'types', './dist/types/index.d.ts').
 
-% The type definitions entrypoint the package must be `./dist/index.d.ts`.
-gen_enforced_field(WorkspaceCwd, 'types', './dist/index.d.ts').
+% The entrypoint for the package must be `./dist/cjs/index.js`.
+gen_enforced_field(WorkspaceCwd, 'main', './dist/cjs/index.js').
+
+% The module entrypoint for the package must be `./dist/esm/index.js`.
+gen_enforced_field(WorkspaceCwd, 'module', './dist/esm/index.js').
 
 % The list of files included in the package must only include files generated
 % during the build step.
-gen_enforced_field(WorkspaceCwd, 'files', ['dist/']).
+gen_enforced_field(WorkspaceCwd, 'files', ['dist/cjs/**', 'dist/esm/**', 'dist/types/**']).
 
 % If a dependency is listed under "dependencies", it should not be listed under
 % "devDependencies".

package.json

@@ -11,15 +11,22 @@
     "url": "https://github.com/MetaMask/metamask-module-template.git"
   },
   "sideEffects": false,
-  "main": "./dist/index.js",
-  "types": "./dist/index.d.ts",
+  "main": "./dist/cjs/index.js",
+  "module": "./dist/esm/index.js",
+  "types": "./dist/types/index.d.ts",
   "files": [
-    "dist/"
+    "dist/cjs/**",
+    "dist/esm/**",
+    "dist/types/**"
   ],
   "scripts": {
-    "build": "tsc --project tsconfig.build.json",
+    "build": "yarn build:source && yarn build:types",
+    "build:cjs": "swc src --out-dir dist/cjs --config-file .swcrc.build.json --config module.type=commonjs",
     "build:clean": "rimraf dist && yarn build",
     "build:docs": "typedoc",
+    "build:esm": "swc src --out-dir dist/esm --config-file .swcrc.build.json --config module.type=es6",
+    "build:source": "yarn build:esm && yarn build:cjs",
+    "build:types": "tsc --project tsconfig.build.json",
     "lint": "yarn lint:eslint && yarn lint:constraints && yarn lint:misc --check && yarn lint:dependencies --check && yarn lint:changelog",
     "lint:changelog": "auto-changelog validate",
     "lint:constraints": "yarn constraints",
@@ -39,6 +46,8 @@
     "@metamask/eslint-config-jest": "^11.0.0",
     "@metamask/eslint-config-nodejs": "^11.0.1",
     "@metamask/eslint-config-typescript": "^11.0.0",
+    "@swc/cli": "^0.1.62",
+    "@swc/core": "^1.3.66",
     "@types/jest": "^28.1.6",
     "@types/node": "^16",
     "@typescript-eslint/eslint-plugin": "^5.43.0",
@@ -71,7 +80,8 @@
   },
   "lavamoat": {
     "allowScripts": {
-      "@lavamoat/preinstall-always-fail": false
+      "@lavamoat/preinstall-always-fail": false,
+      "@swc/core": true
     }
   }
 }

tsconfig.build.json

@@ -3,12 +3,21 @@
   "compilerOptions": {
     "declaration": true,
     "declarationMap": true,
+    "emitDeclarationOnly": true,
     "inlineSources": true,
     "noEmit": false,
-    "outDir": "dist",
+    "outDir": "dist/types",
     "rootDir": "src",
     "sourceMap": true
   },
   "include": ["./src/**/*.ts"],
-  "exclude": ["./src/**/*.test.ts"]
+  "exclude": [
+    "./src/**/__fixtures__/**/*",
+    "./src/**/__mocks__/**/*",
+    "./src/**/__test__/**/*",
+    "./src/**/__tests__/**/*",
+    "./src/**/__snapshots__/**/*",
+    "./src/**/*.test.ts",
+    "./src/**/*.test.*.ts"
+  ]
 }