rollup.config.mjs

import replace from '@rollup/plugin-replace'
import resolve from '@rollup/plugin-node-resolve'
import commonjs from '@rollup/plugin-commonjs'
import ts from 'rollup-plugin-typescript2'
import alias from '@rollup/plugin-alias'
import terser from '@rollup/plugin-terser'
import path from 'path'
import { rimraf } from 'rimraf'
import camelCase from 'camelcase'
import pkg from './package.json' with { type: 'json' }

const cwd = process.cwd()

rimraf.sync(path.join(cwd, './dist'))

const banner = `/*!
  * ${pkg.name} v${pkg.version}
  * (c) ${new Date().getFullYear()} Eduardo San Martin Morote
  * @license MIT
  */`

const exportName = camelCase(pkg.name, { pascalCase: true })

function createEntry(
  {
    format, // Rollup format (iife, umd, cjs, es)
    external, // Rollup external option
    input = 'src/index.ts', // entry point
    env = 'development', // NODE_ENV variable
    minify = false,
    isBrowser = false, // produce a browser module version or not
  } = {
    input: 'src/index.ts',
    env: 'development',
    minify: false,
    isBrowser: false,
  }
) {
  // force production mode when minifying
  if (minify) env = 'production'

  const config = {
    input,
    plugins: [
      replace({
        preventAssignment: true,
        values: {
          __VERSION__: pkg.version,
          'process.env.NODE_ENV': `'${env}'`,
        },
      }),
      alias({
        // resolve: ['.ts', '.js'],
        // entries: [{ find: 'firebase', replacement: path.join(__dirname, './stub') }],
      }),
    ],
    output: {
      banner,
      file: `dist/${pkg.name}.UNKNOWN.js`,
      format,
    },
  }

  if (format === 'iife') {
    config.output.file = pkg.unpkg
    config.output.name = exportName
  } else if (format === 'es') {
    config.output.file = pkg.module
  } else if (format === 'cjs') {
    config.output.file = pkg.module.replace('js', 'cjs')
  }

  if (!external) {
    config.plugins.push(resolve(), commonjs())
  } else {
    config.external = external
  }

  config.plugins.push(
    ts({
      // only check once, during the es version with browser (it includes external libs)
      check: !tsChecked,
      tsconfigOverride: {
        exclude: ['__tests__'],
        compilerOptions: {
          // same for d.ts files
          declaration: !tsChecked,
          target: format === 'es' && !isBrowser ? 'esnext' : 'es2015',
        },
      },
    })
  )

  tsChecked = true

  if (minify) {
    config.plugins.push(
      terser({
        module: format === 'es',
      })
    )
    config.output.file = config.output.file.replace(/\.([mc]?js)$/i, '.prod.$1')
  }

  return config
}

let tsChecked = false

const builds = [
  createEntry({ format: 'cjs' }),
  createEntry({ format: 'es' }),
  createEntry({ format: 'cjs', minify: true }),
]

if (pkg.unpkg)
  builds.push(
    createEntry({ format: 'iife' }),
    createEntry({ format: 'iife', minify: true }),
    createEntry({ format: 'es', minify: true })
  )

export default builds