title: ExtJS alias vs id
body: <p>I don't understand the usage of <a href="http://docs.sencha.com/extjs/4.2.1/#!/api/Ext.Class-cfg-alias" rel="nofollow">alias</a> vs id vs itemId config properties in ExtJS</p>
  
  <p><em>app/view/foo.js</em></p>
  
  <pre><code>Ext.define('app.view.foo', {
      ...
      alias: 'widget.foo',         // 1
      id: 'foo',                   // or 2
      ...
  });
  </code></pre>
  
  <p><em>app/controller/goo.js</em></p>
  
  <pre><code>Ext.define('app.controller.goo', {
      ...
      views: ['foo', ...],
      init: function() {
          this.control({
                 'foo': {...},     // 1
                 '#foo': {...}     // or 2
                 ...
          });
          ...
      },
      ...
  });
  </code></pre>
  
  <p>With <code>alias</code> I can use <code>xtype</code> easily.. but what advantage do I gain by setting <code>id</code>'s to my views?</p>