Angular: Empty Fiddle

http://angularjs.org/

HTML

<script src="http://code.angularjs.org/angular-1.0.1.js"></script>
<div ng-controller="MyCtrl">
  <p ng-show="getFooUndef(foo)">Show this if $scope.foo === undefined</p>
  Hello, {{foo}} {{angular.isUndefined(foo)}}!
</div>

JavaScript

var myApp = angular.module('myApp',[]);

function MyCtrl($scope) {
    $scope.foo = undefined;

    $scope.getFooUndef = function(foo){
        return ( foo === undefined );
    }
}