CODEWITHSUNDEEP
javascriptbackbone.jsrequirejsdependencies
Sergey Terehin
Sergey Terehin

Reputation: 163

Accessing backbone object inside requireJS without defining it

I use RequireJS with Backbone.js.

In index.html I link require.js and define entry point start.js:

<script src="/app/vendor/require.js" data-main="/app/start"></script>

In start.js I configure RequireJS to access Backbone library with its dependencies:

require.config({
  paths: {
    jquery: 'vendor/jquery',
    underscore: 'vendor/underscore',
    backbone: 'vendor/backbone'
  },
});

To use Backbone module in this file I can define it as a dependency:

require(['backbone'], function (Backbone) {
  console.log(Backbone);
});

But I define as dependancy child module which has Backbone as its dependancy

start.js:

require.config({
  paths: {
    jquery: 'vendor/jquery',
    underscore: 'vendor/underscore',
    backbone: 'vendor/backbone'
  },
});

require(['child'], function (Child) {
  console.log(Backbone);
});

child.js:

define(['backbone'], function (Backbone) {});

Why I can access Backbone module in start.js without defining it? If I will use any other custom module I will receive error. This works only with Backbone module.

Upvotes: 0

Views: 247

Answers (1)

Louis
Louis

Reputation: 151380

Your require calls requires your child module, which requires backbone, so by the time child is loaded and the callback executes, the backbone module has been loaded. Now, let's see what this module does:

if (typeof define === 'function' && define.amd) {
  define(['underscore', 'jquery', 'exports'], function(_, $, exports) {
    // Export global even in AMD case in case this script is loaded with
    // others that may still expect a global Backbone.
    root.Backbone = factory(root, exports, _, $);
  });
...

As you can see there, even if you load Backbone as an AMD module, it still exports into the global space the symbol Backbone. (The root variable is equivalent to window in a browser or global in Node.js.) This is why your code works.

For my own work, I'd write the call like this:

require(['backbone', 'child'], function (Backbone, Child) {

so as to avoid relying on the global symbol. Future versions of Backbone could cease to export the global symbol when they detect that they are loaded as an AMD module.

Upvotes: 2

Related Questions