Saturday, April 26, 2014

Using Browserify with jQuery, Backbone.js and more.

This article aims to help you understand how to use Browserify in your projects to manage your front-end dependencies, as well as your back-end ones. It assumes you know what Browserify does and that you are confused about exactly how to use in a real project to handle all of your dependencies, particularly with client-side frameworks. I will show examples with jQuery and Backbone.js, but what I explain will apply somewhat to other frameworks and libraries too.

Using Browserify with jQuery

A good first step toward understanding how to use browserify is with jQuery. Delete any script tag's that include jquery.js in your html on the client-side. Instead, install the jquery node module (into ./node_modules) and save a reference to it in package.json:

 $ npm install jquery --save

jQuery 2.1.0 is capable of using browserify's module.exports. That is, you can install the npm package called "jquery" instead of the older workarounds such as the "jquery-browserify" npm package.

jQuery will need a window object:

 var $ = require('jquery');

Older jQuery's will need to do this as var $ = require('jquery')(window);or var $ = require('jquery/dist/jquery')(window);

If you omit the relative path it'll resolve to the module in node_modules, allowing us to just require('jquery') rather than specify a path to jquery.

Whenever any of your JavaScript files need a reference to $ or jQuery, you simply create them as needed, with the above jquery require line -- or with var jQuery = require('jquery'); if you use the name jQuery instead of $.

Now you browserify your code:

 $ npm install -g browserify
 $ browserify whatever.js -o bundle.js

You'll then use a script tag to include bundle.js instead of jquery.js. That's it!

Using Browserify with Backbone.js

Install Backbone.js, Underscore.js and jQuery as node modules:

 $ npm install backbone underscore jquery --save

We explicitly npm installed underscore, instead of letting backbone install it, so that we can require('underscore') later when needed. And we used the --save flag to store these versions in package.json because it's a good habit to get into.

If you structured your Backbone code using a single global object, like app, then you'll need to replace all the lines (if any) that say:

 var app = app || {};

with something like:

 var $ = require('jquery');
 var Backbone = require('backbone');
 var _ = require('underscore');
 Backbone.$ = $;

in all of your JavaScript files. Each file may only need certain objects, and so we should only put the ones each module needs. Being explicit about which dependencies are needed is part of what good modularity is all about. For example, if you only need a reference to Backbone in one file then only do:

 var Backbone = require('backbone');

Backbone can run fine without jQuery, but you can explicitly tell Backbone to use jQuery when needed by doing Backbone.$ = $;

If you explicitly need the '_' object because you're invoking underscore directly, then also include the var _ = require('underscore');

Because of the way Browserify encapsulates every module into its own scope, we no longer have to pass things like jQuery into an IIFE to avoid global conflicts, and we can even put 'use strict' at the TOP of our modules. So instead of:

 var jQuery = require('jquery');
 var Backbone = require('backbone');
 Backbone.$ = jQuery;

 (function($) {
     'use strict';

      module.exports = Backbone.View.extend({

we can simply write:

 'use strict';

 var $ = require('jquery');
 var Backbone = require('backbone');
 Backbone.$ = $;

 module.exports = Backbone.View.extend({ ... });

Notice how the above code also needed var Backbone = require('backbone'); because it references Backbone in this file. Everything not in module.exports will stay private to its module. In Node.JS, module.exports is simply the object that gets returned as the result of a require call.

Next delete any script tags that include your user-defined Backbone javascript files and replace with just:

 <script src="js/bundle.js"></script>

Generate the bundle.js file

 $ browserify ./public/js/app.js -o public/js/bundle.js

If we were using the global app object instead of browserify, we'd have to make sure js/views/app.js gets included before js/app.js in the script tag include order. But with browserify we take care of the ordering differently. For example, in public/js/app.js put:

 var $ = require('jquery');
 AppView = require('./views/app');
 // The only thing that should be in a DOMReady
 $(function() {
     new AppView();

Then in public/js/views/app.js put:

 'use strict';

 var Backbone = require('backbone');
 var $ = require('jquery');
 Backbone.$ = $;

 // examples of requiring some user-defined Backbone stuff
 var Todos = require('../collections/todos');
 var TodoView = require('./todo');

 //var app = app || {};

 //app.AppView = Backbone.View.extend({
 module.exports = Backbone.View.extend({

     initialize: function() {
         //this.listenTo(app.Todos, 'add', this.addTodoTask);
         this.listenTo(Todos, 'add', this.addTodoTask)

Notice how I commented out the old app global object stuff and replaced it with Browserify'd code. You basically just need to replace app.whatever with module.exports = whatever. And for every file that used to reference the global app object, you now need to require() that file and store it in a local object. So continuing the example, above '../collections/todo.js' might contain:

 'use strict';

 var Backbone = require('backbone');
 var Todo = require('../models/todo');
 //var app = app || {};

 var TodoList = Backbone.Collection.extend({
     //model: app.Todo,
     model: Todo,


 module.exports = new TodoList();

Again I commented out the global app object to show that's where browserify's stuff goes.

Since a Backbone.js project can become large, or any project for that matter, it's a good idea to install watchify. It takes the same command-line arguments as browserify but will automatically update the bundle.js file whenever you make changes, and it will update it faster since it only updates the changes.

Additionally, using the power of Browserify transforms, you can integrate Bower packages and more. This is useful if you need a dependency that uses CSS or something that Browserify isn't yet suited for. Perhaps I'll write more about this next time.

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