Gulp javascript task — parcel version

gulpfile.js

let PRODUCTION_MODE = process.argv.indexOf('--minify') !== -1;

const gulp = require('gulp');
const _ = require('gulp-load-plugins')();

gulp.task('javascript', () => {
  const sources = ['./source/js/index.js', 'source/js/sw.js']

  gulp.src(sources, { read: false })
    .pipe(_.parcel({
      minify: PRODUCTION_MODE,
      outDir: './public/assets/js',
    }))
    .pipe(gulp.dest('./public/assets/js'));
});

package.json

{
  "scripts": {
    "build": "gulp --minify"
  },
  "dependencies": {
    "gulp": "^3.9.1",
    "gulp-load-plugins": "^1.5.0",
    "gulp-parcel": "^0.3.5"
  }
}