add build script to make things work everywhere

Just coppying other people's hack go to make a build ts project work on cjs and esm

build.ts

@@ -0,0 +1,84 @@
+/* 
+This script was taken from hono https://github.com/honojs/hono/blob/main/build.ts
+Everything below is theres
+*/
+/*
+  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/**/*.test.ts', './src/mod.ts', './src/middleware.ts', './src/deno/**/*.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${fileExtension}`)
+          if (fs.existsSync(tsPath)) {
+            if (args.path.endsWith('/')) {
+              importPath = `${args.path}index${extension}`
+            } else {
+              importPath = `${args.path}/index${extension}`
+            }
+          }
+        }
+        return { path: importPath, external: true }
+      }
+    })
+  },
+})
+
+const commonOptions: BuildOptions = {
+  entryPoints,
+  logLevel: 'info',
+  platform: 'node',
+  tsconfig: 'tsconfig.json',
+}
+
+const cjsBuild = () =>
+  build({
+    ...commonOptions,
+    outbase: './src',
+    outdir: './dist/cjs',
+    format: 'cjs',
+    tsconfig: 'tsconfig.cjs.json',
+  })
+
+const esmBuild = () =>
+  build({
+    ...commonOptions,
+    bundle: true,
+    outbase: './src',
+    outdir: './dist',
+    format: 'esm',
+    plugins: [addExtension('.js')],
+  })
+
+Promise.all([esmBuild(), cjsBuild()])
+
+exec(`tsc --emitDeclarationOnly --declaration --project tsconfig.build.json`)