Gulp + Browserify + Angularjs

gulpfile.js

var browserify = require('browserify');
var es6ify = require('es6ify');
var gulp = require('gulp');
var source = require('vinyl-source-stream');

gulp.task('build:libs', function(callback) {
    return browserify({
            entries: [
                require('es6ify').runtime,
            ],
            debug: true
        })
        .require(require.resolve('./bower_components/angular/angular.js'), {
            expose: 'angular'
        })
        .bundle()
        .pipe(source('libs.js'))
        .pipe(gulp.dest('./build'))
});

gulp.task('build:scripts', function(callback) {
    return browserify({
            entries: ['./src/main.es6'/*, require('es6ify').runtime*/],
            debug: true
        })
        .transform(require('es6ify').configure(/^(?!.*node_modules)+.+\.es6$/))
        .external('angular')
        // .require(require.resolve('./bower_components/angular/angular.js'), {
        //     expose: 'angular'
        // })
        .bundle()
        .pipe(source('main.js'))
        .pipe(gulp.dest('./build'))
});

gulp.task('build', ['build:libs', 'build:scripts']);