title: How to pluck key value from object of array
body: <p>i have object of array like this:</p>
  
  <pre><code>var arr = [{id: 1, url: 'something'},{id: 2, url: 'something2'}];
  </code></pre>
  
  <p>i want output like this :</p>
  
  <pre><code>[{id:1}, {id:2}]
  </code></pre>
  
  <p>Thanks in advance</p>