gulpfile.js

'use strict'
// Inspired by https://github.com/babel/minify/blob/master/gulpfile.babel.js

const del = require('del')
const through = require('through2')
const newer = require('gulp-newer')
const babel = require('gulp-babel')
const util = require('gulp-util')
const plumber = require('gulp-plumber')
const gulp = require('gulp')
const path = require('path')
const { cyan } = util.colors

const scripts = './packages/*/src/**/*.js'
const builds = './packages/*/build'
const dest = 'packages'

let srcEx, libFragment

if (path.win32 === path) {
  srcEx = /(packages\\[^\\]+)\\src\\/
  libFragment = '$1\\build\\'
} else {
  srcEx = new RegExp('(packages/[^/]+)/src/')
  libFragment = '$1/build/'
}

function build () {
  return gulp
    .src(scripts)
    .pipe(plumber())
    .pipe(through.obj((file, enc, callback) => {
      file._path = file.path
      file.path = file.path.replace(srcEx, libFragment)
      callback(null, file)
    }))
    .pipe(newer(dest))
    .pipe(babel())
    .pipe(gulp.dest(dest))
    .on('end', () => {
      util.log(`Finished '${cyan('build')}'`)
    })
}

gulp.task('build', build)

gulp.task('watch', ['build'], function () {
  gulp.watch(scripts, { debounceDelay: 200 }, build)
})

gulp.task('clean', () => {
  return del(builds)
})