gulp-better-rollup

A Gulp plugin for Rollup ES6 Bundler. This plugin unlike gulp-rollup integrates Rollup deeper into Gulps pipeline chain by taking some of the Rollup API out of your hands in exchange of giving you the full power over the pipeline (to use any gulp plugins).

Installation

npm install gulp-better-rollup --save-dev

Usage

var gulp = require('gulp')
var rename = require('gulp-rename')
var rollup = require('gulp-better-rollup')
var babel = require('rollup-plugin-babel')

gulp.task('lib-build', () => {
  gulp.src('lib/index.js')
    .pipe(sourcemaps.init())
    .pipe(rollup({
      // notice there is no `input` option as rollup integrates into gulp pipeline
      plugins: [babel()]
    }, {
      // also rollups `sourcemap` option is replaced by gulp-sourcemaps plugin
      format: 'cjs',
    }))
    // inlining the sourcemap into the exported .js file
    .pipe(sourcemaps.write())
    .pipe(gulp.dest('dist'))
})

or simply

gulp.task('lib-build', () => {
  gulp.src('lib/mylibrary.js')
    .pipe(sourcemaps.init())
    // note that UMD and IIFE format requires `name` but it was guessed based on source file `mylibrary.js`
    .pipe(rollup({plugins: [babel()]}, 'umd'))
    // save sourcemap as separate file (in the same folder)
    .pipe(sourcemaps.write(''))
    .pipe(gulp.dest('dist'))
})

Usage & Options

rollup([rollupOptions,] generateOptions)

This plugin is based on the standard Rollup options, with following caveats

rollupOptions

First argument is object of options found you would specify as rollup.rollup(options) in Rollup API

input should not be used as the entry file is provided by gulp. It also works with gulp-watch

  gulp.src('src/app.js')
    .pipe(watch('src/*.js'))
    .pipe(rollup({...}, 'umd'))
    .pipe(gulp.dest('./dist'))

But if you really need it for some bizzare reason then you can specify custom entry like so

  gulp.src('src/app.js')
    .pipe(someRealityBendingPlugin(...))
    .pipe(rollup({
      input: 'src/app.js'
    }, 'umd'))
    .pipe(gulp.dest('./dist'))

cache is enabled by default and taken care of by the plugin because usage in cojunction with watchers like gulp-watch is expected. It can be however disabled by settings cache to false

generateOptions

Second argument is object of options describing output format of the bundle. It's the same thing you would specify as bundle.generate(options) in Rollup API or as a single item of targets in rollup.config.js

name and amd.id are by default assigned by filename but can be explicitly specified

Caveat: Exporting to UMD or IIFE format requires to specify name. This plugin takes care of autoassigning it based on filename. But if your main file is named index.js or main.js then your module will be also named index or main.

Caveat: If you don't want amd.id to be automatically assigned for your AMD modules, set amd.id to empty string .pipe(rollup({amd:{id:''}}))

intro/outro are discouraged to use in favor of gulps standard plugins like gulp-header and gulp-footer

sourcemap option is omitted. Use the standard gulp-sourcemaps plugin instead.

sourcemapFile is unvailable as well.

shortcuts

If you don't need to define plugins like babel, use external modules, explicitly specify input file, or any other options of rollupOptions object, you can just skip this first argument alltogether. Also generateOptions can be replaced by string of module format if you only export in a single format.

gulp.task('dev', function() {
  gulp.src('lib/mylib.js')
    .pipe(rollup('es'))
    .pipe(gulp.dest('dist'))
})

Both rollupOptions and generateOptions can be also specified as a single object if you preffer simplicity over semantically relying on the Rollup JS API. This could also come in handy as setting defaults for generateOptions when you export multiple formats and you don't want to copy-paste the same exports and blobal options.

gulp.task('dev', function() {
  gulp.src('lib/mylib.js')
    .pipe(rollup({
      treeshake: false,
      plugins: [require('rollup-plugin-babel')],
      external: ['first-dep', 'OtherDependency'],
    }, {
      name: 'CustomModuleName',
      format: 'umd',
    }))
    .pipe(gulp.dest('dist'))
})

Can be simplified into

gulp.task('dev', function() {
  gulp.src('lib/mylib.js')
    .pipe(rollup({
      treeshake: false,
      plugins: [require('rollup-plugin-babel')],
      external: ['first-dep', 'OtherDependency'],
      name: 'CustomModuleName',
      format: 'umd',
    }))
    .pipe(gulp.dest('dist'))
})

exporting multiple bundles

Array of generateOptions can be provided to export into multiple formats.

var pkg = require('./package.json')
gulp.task('build', function() {
  gulp.src('lib/mylib.js')
    .pipe(sourcemaps.init())
    .pipe(rollup(rollupOptions, [{
      file: pkg['jsnext:main'],
      format: 'es',
    }, {
      file: pkg['main'],
      format: 'umd',
    }]))
    .pipe(sourcemaps.write(''))
    .pipe(gulp.dest('dist'))
})

Caveat 1: file can take path instead of just a file name, but the file won't be saved there. Exporting files from gulp always relies on the .pipe(gulp.dest(...)) and not the plugin itself.

Caveat 2: gulp-sourcemaps plugin doesn't (yet) support the .mjs extension you might want to use to export ES format into. Specifically it can inline the sourcemap into the bundle file (using sourcemaps.write()), and it can also create external sourcemap file with sourcemaps.write(PATH_TO_SOURCEMAP_FOLDER), it just won't insert the //# sourceMappingURL= linking comment at the end of your .mjs file, effectivelly rendering the sourcemap useless.