title: Filter array based on an array of index
body: <p>First I apologize if it's a duplicate (I searched but did not find this simple example...), but I want to select elements of <code>arr1</code> based on the index in <code>arr2</code>:</p>
  
  <pre><code>arr1 = [33,66,77,8,99]
  arr2 = [2,0,3] 
  </code></pre>
  
  <p>I am using <code>underscore.js</code> but the <code>0</code> index is not retrieved (seems to be considered as <code>false</code>):</p>
  
  <pre><code>res = _.filter(arr1, function(value, index){
      if(_.contains(arr2, index)){
          return index;
      }
  });
  </code></pre>
  
  <p>Which returns:</p>
  
  <pre><code># [77, 8]
  </code></pre>
  
  <p>How could I fix this, and is there a simpler way to filter using an array of indexes? I am expecting the following result:</p>
  
  <pre><code># [77, 33, 8]
  </code></pre>