browserify + babel

compile.js

var fs = require("fs");

var browserify = require("browserify"),
    babelify = require("babelify"),
    watchify = require('watchify'),
    partialify =  require('partialify');

var input = './www/js/commonjs/app.js',
    output = './www/bundle.js',
    debug = true;

// define transformations
var b = browserify(input, {
    debug: debug,
    verbose: true,
    extensions: ['.js', '.es6', '.jsx']
})
.transform(babelify.configure({
    extensions: ['.js', '.es6', '.jsx'],
    stage: 0
}))
// html templates and more
.transform(partialify)
.on("error", function (err) {
    console.log("Error : " + err.message);
});

// watch sources
var w = watchify(b, {
    verbose: true,
    debug: debug,
    poll: true
})
.on("log", function (msg) { console.log(msg); })
.on("update", function(ids) {
    console.log('update bundle: ' + ids.length + ' files');
})
.bundle()
.pipe(fs.createWriteStream(output));