feat: support ESM

build.ts

@@ -0,0 +1,73 @@
+/*
+  This script is heavily inspired by `built.ts` used in @kaze-style/react.
+  https://github.com/taishinaritomi/kaze-style/blob/main/scripts/build.ts
+  MIT License
+  Copyright (c) 2022 Taishi Naritomi
+*/
+
+import { exec } from 'child_process'
+import fs from 'fs'
+import path from 'path'
+import { build } from 'esbuild'
+import type { Plugin, PluginBuild, BuildOptions } from 'esbuild'
+import glob from 'glob'
+
+const entryPoints = glob.sync('./src/**/*.ts', {
+  ignore: ['./src/types.ts'],
+})
+
+/*
+  This plugin is inspired by the following.
+  https://github.com/evanw/esbuild/issues/622#issuecomment-769462611
+*/
+const addExtension = (extension: string = '.js', fileExtension: string = '.ts'): Plugin => ({
+  name: 'add-extension',
+  setup(build: PluginBuild) {
+    build.onResolve({ filter: /.*/ }, (args) => {
+      if (args.importer) {
+        const p = path.join(args.resolveDir, args.path)
+        let tsPath = `${p}${fileExtension}`
+
+        let importPath = ''
+        if (fs.existsSync(tsPath)) {
+          importPath = args.path + extension
+        } else {
+          tsPath = path.join(args.resolveDir, args.path, `index${fileExtension}`)
+          if (fs.existsSync(tsPath)) {
+            importPath = `${args.path}/index${extension}`
+          }
+        }
+        return { path: importPath, external: true }
+      }
+    })
+  },
+})
+
+const commonOptions: BuildOptions = {
+  entryPoints,
+  logLevel: 'info',
+  platform: 'node',
+}
+
+const cjsBuild = () =>
+  build({
+    ...commonOptions,
+    outbase: './src',
+    outdir: './dist',
+    format: 'cjs',
+  })
+
+const esmBuild = () =>
+  build({
+    ...commonOptions,
+    bundle: true,
+    outbase: './src',
+    outdir: './dist',
+    format: 'esm',
+    outExtension: { '.js': '.mjs' },
+    plugins: [addExtension('.mjs')],
+  })
+
+Promise.all([esmBuild(), cjsBuild()])
+
+exec(`tsc --emitDeclarationOnly --declaration`)

package.json

@@ -10,10 +10,19 @@
   "exports": {
     ".": {
       "types": "./dist/index.d.ts",
-      "default": "./dist/index.js"
+      "require": "./dist/index.js",
+      "import": "./dist/index.mjs"
     },
-    "./serve-static": "./dist/serve-static.js",
-    "./vercel": "./dist/vercel.js"
+    "./serve-static": {
+      "types": "./dist/serve-static.d.ts",
+      "require": "./dist/serve-static.js",
+      "import": "./dist/serve-static.mjs"
+    },
+    "./vercel": {
+      "types": "./dist/vercel.d.ts",
+      "require": "./dist/vercel.js",
+      "import": "./dist/vercel.mjs"
+    }
   },
   "typesVersions": {
     "*": {
@@ -30,7 +39,7 @@
   },
   "scripts": {
     "test": "jest",
-    "build": "rimraf dist && tsc",
+    "build": "rimraf dist && tsx ./build.ts",
     "postbuild": "publint",
     "prerelease": "yarn build && yarn test",
     "release": "np"
@@ -51,16 +60,19 @@
   },
   "dependencies": {},
   "devDependencies": {
+    "@types/glob": "^8.1.0",
     "@types/jest": "^29.5.3",
     "@types/node": "^18.7.16",
     "@types/supertest": "^2.0.12",
+    "esbuild": "^0.18.13",
     "hono": "^3.3.0",
     "jest": "^29.6.1",
     "np": "^7.7.0",
     "publint": "^0.1.16",
     "rimraf": "^3.0.2",
     "supertest": "^6.2.4",
     "ts-jest": "^29.1.1",
+    "tsx": "^3.12.7",
     "typescript": "^4.8.3"
   }
-}
+}