task-app.js

var gulp        = require('gulp'),
    gutil       = require('gulp-util'),
    watchify    = require("watchify"),
    concat      = require("gulp-concat"),
    streamqueue = require('streamqueue'),
    streamify   = require('gulp-streamify'),
    source      = require('vinyl-source-stream'),
    livereload  = require('gulp-livereload');

/**
 * Create a single file app.js
 */
module.exports = function(server, templates) {

    // Concatenate your app and build an app.js
    var bundler = watchify('./src/scripts/core/core.js');

    bundler.on('update',rebundle);

    function rebundle(file) {

        if(file) {
            file.forEach(function (fileName) {
                gutil.log('File updated', gutil.colors.yellow(fileName));
            });
        }

        var stream = streamqueue({objectMode: true});
        stream.queue(templates());
        stream.queue(bundler
            .bundle({
                debug: (gutil.env.type !== 'prod')
            })
            .on("error", function(err) {
                gutil.log("Browserify error:", err);
            })
            .pipe(source("app.js")));
        return stream.done()
            .pipe(streamify(concat('app.js')))
            .pipe(gulp.dest('./app/js'))
            .pipe(livereload(server));
    }

    return rebundle();
};