Gulp browserify watchify task(s)

browserify.js

"use strict";

var gulp = require('gulp');
// plugins
var plumber = require('gulp-plumber');
var uglify = require('gulp-uglify');
var notify = require('gulp-notify');
var sourcemaps = require('gulp-sourcemaps');
// deps
var source = require('vinyl-source-stream');
var buffer = require('vinyl-buffer');
var watchify = require('watchify');
var browserify = require('browserify');
// utils
var handleErrors = require('../util/handleErrors');
var onSuccess = require('../util/onSuccess');

var bundler;
var buildOnce = false;

var b = browserify({
    cache: {},
    packageCache: {},
    fullPaths: true,
    extensions: ['.js'],
    debug: true
});

var browserifyTask = function() {
    buildOnce = true;
    bundler = b;
    bundler.add('./src/js/main.js');

    return rebundle();
};

var watchifyTask = function() {
    bundler = watchify(b);
    bundler.on('update', rebundle);
    bundler.add('./src/js/main.js');

    return rebundle();
};

function rebundle() {
    return bundler.bundle()
        .on('error', handleErrors)
        .pipe(plumber())
        .pipe(source('bundle.js'))
        .pipe(buffer())
        .pipe(sourcemaps.init({
            loadMaps: true
        }))
        .pipe(uglify({
            mangle: false
        }))
        .pipe(sourcemaps.write('./'))

    .pipe(gulp.dest('./dist/js/'))
        .pipe(notify(onSuccess));
}

gulp.task('browserify', browserifyTask);
gulp.task('watchify', watchifyTask);