How to build a TypeScript library with Vite

I recently moved a few TypeScript libraries from Microbundle, TSDX and dts-cli to Vite. I wanted more control over the build setup, and to be able to develop, build and test1 them using the same configuration.

The secret is to use Vite’s library mode, and externalize all dependencies and built-in Node.js modules so that they are not bundled with your code:

// vite.config.js
import { defineConfig } from 'vite'
import dts from 'vite-plugin-dts'
import pkg from './package.json' assert { type: 'json' }

export default defineConfig({
  build: {
    lib: {
      entry: './src/index.ts',
      formats: ['es'], // pure ESM package
    rollupOptions: {
      external: [
        ...Object.keys(pkg.dependencies), // don't bundle dependencies
        /^node:.*/, // don't bundle built-in Node.js modules (use protocol imports!)
    target: 'esnext', // transpile as little as possible
  plugins: [dts()], // emit TS declaration files

You will also need a tsconfig.json specifying root files and compiler options. If you don’t have one yet, you can generate one with the appropriate create-vite TypeScript template, e.g. vanilla-ts.


  1. I got tired of trying to make Jest work, especially after my migrations to ESM. Adopting Vitest, with its compatible API and unified configuration with Vite, was a no-brainer.