rollup.config.js

import nodeResolve from 'rollup-plugin-node-resolve';
import babel from 'rollup-plugin-babel';
import replace from 'rollup-plugin-replace';
import uglify from 'rollup-plugin-uglify';

var env = process.env.NODE_ENV
var config = {
  format: 'umd',
  moduleName: 'ReduxSaga',
  exports: 'named',
  plugins: [
    nodeResolve({
      jsnext: true,
    }),
    babel({
      exclude: 'node_modules/**',
      plugins: ['external-helpers'],
    }),
    replace({
      'process.env.NODE_ENV': JSON.stringify(env),
    }),
  ],
}

if (env === 'production') {
  config.plugins.push(
    uglify({
      compress: {
        pure_getters: true,
        unsafe: true,
        unsafe_comps: true,
        warnings: false,
        screw_ie8: true,
      },
      mangle: {
        screw_ie8: true,
      },
      output: {
        screw_ie8: true,
      },
    })
  )
}

export default config