AngularJS Example:

HTML

<div ng-app="app">
  <p id="test-{{ foo }}">Test Element</p>
  <selector for="test-{{ foo }}"></selector>
</div>

CSS

</style> <!-- Ugly Hack due to jsFiddle issue: http://goo.gl/BUfGZ --> 
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.26/angular.min.js"></script>
<style>

JavaScript

angular.module('app', [])
  .run(function($rootScope) {
    $rootScope.foo = 'bar'
  })
  .directive('selector', function($templateCache) {
    return {
      restrict: 'E',
      scope: {
        query: '@for'
      },
      link: function($scope, $element) {
        var id = $element.parent().children().eq(0).attr('id');
        var foundElement = !!document.getElementById($scope.query);
        $element.text('Try to get element with id "' + id + '" with query "' + $scope.query + '"? ' + foundElement + '.');
      }
    };
  });