Test esbuild to generate ESModule and CommonJS

tools/esbuild.js

@@ -0,0 +1,28 @@
+import { build } from 'esbuild'
+import { nodeExternalsPlugin } from 'esbuild-node-externals'
+
+const baseConfig = {
+  entryPoints: ['lib/index.js'],
+  platform: 'node',
+  target: 'node14',
+  bundle: true,
+  minify: false,
+  sourcemap: false,
+  legalComments: 'none',
+  plugins: [nodeExternalsPlugin()]
+}
+
+const moduleConfig = {
+  ...baseConfig,
+  outfile: 'dist/index.mjs',
+  format: 'esm'
+}
+
+const legacyConfig = {
+  ...baseConfig,
+  outfile: 'dist/index.cjs',
+  format: 'cjs'
+}
+
+build(moduleConfig).then(() => { }).catch(() => { process.exit(1) })
+build(legacyConfig).then(() => { }).catch(() => { process.exit(1) })