Question

From the Ember.js documentation:

Person = Ember.Object.extend({
   // [..]
});

It’s the first definition of Person, so why is the var statement omitted?

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var is also missing in some other places, e.g. Ember.Application.Create or Ember.StateManager.Create.

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Guys, I know what happens when var is omitted. But there doesn’t seem to be a good reason to do it, like this it’s just confusing people.

Answer 1

It’s declared globally so Ember and Handlebars can resolve bindings.

In case of a view for example it’s necessary so it can be instantiated in a Handlebars template via the view helper:

Handlebars:

<script type="text/x-handlebars" >
    {{#view MyView}}
         my view's template
    {{/view}}
</script>

JavaScript:​

MyView = Ember.View.extend({});

---

The following example doesn’t work when the controller is declared with a var statement, see http://jsfiddle.net/pangratz666/uzsd6/:

Handlebars:

<script type="text/x-handlebars" >
    {{controller.name}} - {{secondController.name}}
</script>​

JavaScript:

var controller = Ember.Object.create({
    name: 'my name'
});

var secondController = Ember.Object.create({
    nameBinding: 'controller.name'
});​

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If the controllers are declared on a global available object, the App namespace in this case, the the bindings can be resolved, see http://jsfiddle.net/pangratz666/kUmje/:

Handlebars:

<script type="text/x-handlebars" >
    {{App.controller.name}} - {{App.secondController.name}}
</script>​

JavaScript:

App = Ember.Application.create({});

App.controller = Ember.Object.create({
    name: 'my name'
});

App.secondController = Ember.Object.create({
    nameBinding: 'App.controller.name'
});​

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You should take a look at the Emberist ‘s blog about Naming Conventions in Ember.js.