build.js

var rollup = require('rollup').rollup;
var npm = require('rollup-plugin-node-resolve');
var commonjs = require('rollup-plugin-commonjs');

console.log("Creating rollup bundle")

rollup({
  entry: './lib/sofe.js',
  plugins: [
    npm({
      // use "jsnext:main" if possible
      // – see https://github.com/rollup/rollup/wiki/jsnext:main
      jsnext: true,

      // use "main" field or index.js, even if it's not an ES6 module
      // (needs to be converted from CommonJS to ES6
      // – see https://github.com/rollup/rollup-plugin-commonjs
      main: true

      // if there's something your bundle requires that you DON'T
      // want to include, add it to 'skip'
      // skip: [ 'some-big-dependency' ],
    }),
    commonjs(),
  ]
}).then( function(bundle) {
  bundle.write({ dest: 'dist/sofe.js', format: 'cjs' })
  console.log("Wrote rollup bundle into dist")
})
.catch(function(err) {
  setTimeout(function() {
    throw err;
  });
});