title: AngularJS - filter for undefined properties in ng-repeat?
body: <p>For my AngularJS project (v1.2.3), I have a list of routes and am trying to build a navigation bar from the object.  What I want to do is display any object with an undefined <code>isRight</code> property in one style, and where the property is defined in another.</p>
  
  <p>In one <code>ng-repeat</code> I would like to filter those objects with an undefined <code>isRight</code> property.  How can I accomplish this inside the <code>ng-repeat</code> attribute, without having to resort to creating a custom filter function?</p>
  
  <pre><code>$scope.nav = [
      { path: '/', title: 'Home' },
      { path: '/blog', title: 'Blog' },
      { path: '/about', title: 'About' },
      { path: '/login', title: 'Login', isRight: true }
  ];
  </code></pre>
  
  <p>I realize I could just add the attribute <code>isRight: false</code> to each object, or have separate nav objects for right and left side links, and other such simple workarounds, but I am curious if there is a way to accomplish this with the current structure, using something along the lines of:</p>
  
  <pre><code>&lt;li ng-repeat="link in nav | filter:{isRight:undefined}"&gt;
  </code></pre>
  
  <p>This is more a curiosity than a need, but I appreciate any suggestions.</p>