async function build(inputOptions, outputOptions) {
  const input = Object.assign(
    {
      plugins: [
        commonjs(), // We can remove this plugin if there are no more CommonJS modules
        resolve(), // We need this plugin only to build the test script
        babel({
          exclude: 'node_modules/**'
        })
      ]
    },
    inputOptions
  );

  const output = Object.assign(
    {
      format: 'umd'
    },
    outputOptions
  );

  const bundle = await rollup(input);
  await bundle.write(output);
}
async function build(inputOptions, outputOptions) {
  const input = Object.assign(
    {
      plugins: [
        commonjs(), // We can remove this plugin if there are no more CommonJS modules
        resolve(), // We need this plugin only to build the test script
        babel({
          exclude: 'node_modules/**'
        })
      ]
    },
    inputOptions
  );

  const output = Object.assign(
    {
      format: 'umd'
    },
    outputOptions
  );

  const bundle = await rollup(input);
  await bundle.write(output);
}
async function build ( inputOptions , outputOptions ) { const input = Object . assign ( { plugins : [ commonjs ( ) , // We can remove this plugin if there are no more CommonJS modules resolve ( ) , // We need this plugin only to build the test script babel ( { exclude : 'node_modules/**' } ) ] } , inputOptions ) ; const output = Object . assign ( { format : 'umd' } , outputOptions ) ; const bundle = await rollup ( input ) ; await bundle . write ( output ) ; }
Only needed for test build 
Build using rollup.js

@see https://rollupjs.org/#javascript-api

@param inputOptions
@param outputOptions
@returns Promise
Only needed for test build Build using rollup . js
Build the test script