rollup /w gulp

gulpfile.js

'use strict';

const browserSync  = require( 'browser-sync' ).create();

const gulp         = require( 'gulp' );
const gulpif       = require( 'gulp-if' );
const rename       = require( 'gulp-rename' );
const uglify       = require( 'gulp-uglify' );
const rollup       = require( 'rollup' );
const rollupStream = require( 'rollup-stream' );
const commonjs     = require( 'rollup-plugin-commonjs' );
const nodeResolve  = require( 'rollup-plugin-node-resolve' );
const babel        = require( 'rollup-plugin-babel' );
const source       = require( 'vinyl-source-stream' );
const buffer       = require( 'vinyl-buffer' );

const sass         = require( 'gulp-sass' );
const postcss      = require( 'gulp-postcss' );
const autoprefixer = require( 'autoprefixer' );
const csswring     = require( 'csswring' );
const plumber      = require( 'gulp-plumber' );

const runSequence  = require( 'run-sequence' ).use( gulp );

let production = false;
let cache;

const AUTOPREFIXER_BROWSERS = {
	browsers: [
		'ie >= 11',
		'safari >= 8',
		'ios >= 8',
		'android >= 4',
	]
};

gulp.task( 'browser-sync', () => {

	browserSync.init( {
		server: {
			baseDir: './',
			directory: true
		},
		startPath: './'
	} );

} );

gulp.task( 'sass', () => {

	const processors = [
		autoprefixer( AUTOPREFIXER_BROWSERS ),
		csswring
	];

	return gulp.src( './src/scss/main.scss' )
	.pipe( plumber( {
		errorHandler: ( err ) => {

			console.log( err.messageFormatted );
			this.emit( 'end' );

		}
	} ) )
	.pipe( sass() )
	.pipe( gulp.dest( './build/css/' ) )
	.pipe( rename( { extname: '.min.css' } ) )
	.pipe( postcss( processors ) )
	.pipe( gulp.dest( './build/css/' ) );

} );

gulp.task( 'rollup', () => {

	return rollupStream( {
		entry: './src/js/main.js',
		rollup: rollup,
		format: 'iife',
		banner: '// @yomotsu',
		cache: cache,
		plugins: [
			replace( {
				'process.env.NODE_ENV': JSON.stringify( 'production' )
			} ),
			babel( {
				exclude: 'node_modules/**',
				presets: [ [ 'es2015', { 'loose' : true, 'modules': false } ] ],
				plugins: [
					// for IE9
					// see https://gist.github.com/zertosh/4f818163e4d68d58c0fa
					'transform-proto-to-assign',
					// 'transform-object-assign'
				]
			} ),
			nodeResolve( {
				browser: true,
				preferBuiltins: false,
			} ),
			commonjs( {
				include: ['node_modules/**'],
				exclude: [],
				sourceMap: false,
			} )
		]
	} )
	.on( 'error', function( err ) {

		console.log( 'Error : ' + err.message );
		this.emit( 'end' );

	} )
	.on( 'bundle', ( bundle ) => { cache = bundle; } )
	.pipe( source( 'main.js' ) )
	.pipe( gulp.dest( './build/js/' ) )
	.pipe( gulpif( production, buffer() ) )
	.pipe( gulpif( production, uglify( { preserveComments: 'some' } ) ) )
	.pipe( rename( { extname: '.min.js' } ) )
	.pipe( gulp.dest( './build/js/' ) );

} );



gulp.task( 'watch', () => {

	gulp.watch( [ './src/js/**/*.js' ], () => {
		runSequence( 'rollup', browserSync.reload );
	} );

	gulp.watch( [ './src/scss/**/*.scss' ], () => {
	  runSequence( 'sass', browserSync.reload );
	} );

} );


gulp.task( 'build', ( callback ) => {

	production = true;
	return runSequence( 'sass', 'rollup', callback );

} );

gulp.task( 'default', ( callback ) => {

	return runSequence( 'browser-sync', 'sass', 'rollup', 'watch', callback );

} );

package.json

{
  "name": "x",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "autoprefixer": "^6.6.0",
    "babel-plugin-transform-proto-to-assign": "^6.9.0",
    "babel-preset-es2015": "^6.18.0",
    "browser-sync": "^2.18.5",
    "csswring": "^5.1.1",
    "gulp": "^3.9.1",
    "gulp-if": "^2.0.2",
    "gulp-plumber": "^1.1.0",
    "gulp-postcss": "^6.2.0",
    "gulp-rename": "^1.2.2",
    "gulp-sass": "^3.0.0",
    "gulp-uglify": "^2.0.0",
    "rollup": "^0.38.1",
    "rollup-plugin-babel": "^2.7.1",
    "rollup-plugin-commonjs": "^6.0.1",
    "rollup-plugin-node-resolve": "^2.0.0",
    "rollup-plugin-replace": "^1.1.1",
    "rollup-stream": "^1.16.0",
    "run-sequence": "^1.2.2",
    "stream-browserify": "^2.0.1",
    "vinyl-buffer": "^1.0.0",
    "vinyl-source-stream": "^1.1.0"
  }
}