gulp-babel-external-helpers

For Babel 5, use gulp-babel-external-helpers@1.x! Versions >=2 are only compatible with Babel 6.

Gulp plugin to output external helpers for Babel to a separate file.

Usage

Note: Usage with watch plugins like gulp-changed and gulp-newer is not supported, but there are workarounds.

var babel = require('gulp-babel')
var babelHelpers = require('gulp-babel-external-helpers')

gulp.task('build', function () {
  return gulp.src('src/')
    .pipe(babel({ externalHelpers: true }))
    .pipe(babelHelpers('babelHelpers.js'))
    .pipe(gulp.dest('lib/'))
})

API

babelHelpers(fileName='babelHelpers.js', outputType='global')

For documentation on the outputType parameter, see the Babel 5 docs. (This behaviour is the same in both Babel 5 and 6.)

Usage with gulp-changed, gulp-newer

Usage with plugins like gulp-changed and gulp-newer is not supported. Both gulp-babel and gulp-babel-external-helpers need to process all files in your task to be able to include all the necessary helpers. With a plugin like gulp-newer, only the changed files will be processed, and only helpers used in the changed files will be included in the generated file.

If your tasks are small, you could create a separate watch build task, and a 'normal' build task that always processes every file:

var gulp = require('gulp')
var newer = require('gulp-newer')
var babel = require('gulp-babel')
var babelHelpers = require('gulp-babel-external-helpers')
 
var src = 'src/**/*.js'
var dest = 'lib/'
 
// Use external helpers when running "gulp build"
gulp.task('build', function () {
  return gulp.src(src)
    .pipe(babel({ externalHelpers: true }))
    .pipe(babelHelpers('babelHelpers.js'))
    .pipe(dest)
})
 
// Use the inline helpers when watching
gulp.task('watch:build', function () {
  return gulp.src(src)
    .pipe(newer(dest))
    .pipe(babel({ externalHelpers: false }))
    .pipe(dest)
})
 
gulp.task('watch', function () {
  gulp.watch([src], ['watch:build'])
})

If your build tasks are more complex and you're using gulp-newer for your watch task only, you can use gulp-if to conditionally use gulp-babel-external-helpers:

var gulp = require('gulp')
var gulpif = require('gulp-if')
var newer = require('gulp-newer')
var babel = require('gulp-babel')
var babelHelpers = require('gulp-babel-external-helpers')
 
var watching = false
 
var src = 'src/**/*.js'
var dest = 'lib/'
 
gulp.task('build', function () {
  return gulp.src(src)
    .pipe(gulpif(watching, newer(dest)))
    .pipe(somePlugin())
    .pipe(someOtherPlugin())
    // Use the inline helpers when watching, but external helpers when doing a
    // full build.
    .pipe(babel({ externalHelpers: !watching }))
    .pipe(gulpif(!watching, babelHelpers('babelHelpers.js')))
    .pipe(gulp.dest(dest))
})
 
gulp.task('watch', function () {
  watching = true
  gulp.watch([src], ['build'])
})

License

MIT