rollup.config.js

import resolve from 'rollup-plugin-node-resolve'
import commonjs from 'rollup-plugin-commonjs'
import typescript from 'rollup-plugin-typescript2'
import { terser } from 'rollup-plugin-terser'

import pkg from './package.json'

export default [
  // CommonJS (for Node) and ES module (for bundlers) build.
  // (We could have three entries in the configuration array
  // instead of two, but it's quicker to generate multiple
  // builds from a single configuration where possible, using
  // an array for the `output` option, where we can specify
  // `file` and `format` for each target)
  {
    input: 'src/index.ts',
    external: ['ms'],
    output: [{ file: pkg.main, format: 'cjs', sourcemap: true }],
    plugins: [
      resolve({ preferBuiltins: false }), // so Rollup can find `ms`
      typescript(/*{ plugin options }*/),
      terser()
    ],
    external: Object.keys(pkg.dependencies)
  }
]