build.mjs

import esbuild from "esbuild";
import { nodeExternalsPlugin } from "esbuild-node-externals";

const entryFile = "src/index.ts";
const sharedBuildProps = {
  bundle: true,
  entryPoints: [entryFile],
  logLevel: "info",
  minify: true,
  sourcemap: true,
  plugins: [nodeExternalsPlugin()],
};

// ESM
esbuild
  .build({
    ...sharedBuildProps,
    format: "esm",
    outfile: "./dist/index.esm.js",
    target: ["esnext"],
    loader: { ".ts": "ts", ".tsx": "tsx" },
  })
  .then(() => console.log("⚡ ESM Done"))
  .catch(() => process.exit(1));

// CJS
esbuild
  .build({
    ...sharedBuildProps,
    format: "cjs",
    outfile: "./dist/index.cjs.js",
    target: ["esnext"],
    loader: { ".ts": "ts", ".tsx": "tsx" },
  })
  .then(() => console.log("⚡ CJS Done"))
  .catch(() => process.exit(1));