gulp & browserify (+watchify +babelify)

gulp.js

const config = require('../config');
const path = config.options.paths;
const gulp = require('gulp');
const browserify = require('browserify');
const watchify = require('watchify');
const babelify = require('babelify');
const source = require('vinyl-source-stream');
const buffer = require('vinyl-buffer');
const merge = require('utils-merge');
const rename = require('gulp-rename');
var uglify = require('gulp-uglify');
const sourcemaps = require('gulp-sourcemaps');

/* nicer browserify errors */
const gutil = require('gulp-util');
const chalk = require('chalk');

const babelifyOpts = {
	presets: ['es2015', 'stage-0']
};

gulp.task('js:watch', function () {
	let args = merge(watchify.args, {debug: true});
	let bundler = watchify(browserify(path.src + '/js/main.js', args)).transform(babelify, babelifyOpts);

	bundle_js(bundler);

	bundler.on('update', function () {
		bundle_js(bundler)
	})
});

// Without watchify
gulp.task('js:dev', function () {
	let bundler = browserify(path.src + '/js/main.js', {
		debug: true
	}).transform(babelify, babelifyOpts);

	return bundle_js(bundler)
});

// Without sourcemaps
gulp.task('js:dist', function () {
	let bundler = browserify(path.src + '/js/main.js').transform(babelify, babelifyOpts);

	return bundler
		.require('./' + path.src + '/js/app.js', {expose: 'app'})
		.bundle()
		.on('error', map_error)
		.pipe(source('main.js'))
		.pipe(buffer())
		.pipe(uglify())
		.pipe(gulp.dest(path.dev + '/js'))
});

function bundle_js(bundler) {
	return bundler
		.require('./' + path.src + '/js/app.js', {expose: 'app'})
		.bundle()
		.on('error', map_error)
		.pipe(source('main.js'))
		.pipe(buffer())
		.pipe(gulp.dest(path.dev + '/js'))
		.pipe(sourcemaps.init({loadMaps: true}))
		.pipe(uglify())
		.pipe(sourcemaps.write('.'))
		.pipe(gulp.dest(path.dev + '/js'))
}

function map_error(err) {
	if (err.fileName) {
		// regular error
		gutil.log(chalk.red(err.name)
			+ ': '
			+ chalk.yellow(err.fileName.replace(path.src + '/js', ''))
			+ ': '
			+ 'Line '
			+ chalk.magenta(err.lineNumber)
			+ ' & '
			+ 'Column '
			+ chalk.magenta(err.columnNumber || err.column)
			+ ': '
			+ chalk.blue(err.description))
	} else {
		// browserify error..
		gutil.log(chalk.red(err.name)
			+ ': '
			+ chalk.yellow(err.message))
	}

	this.emit('end');
}