title: Create new array without impacting values from old array
body: <p>I'm trying to create a copy of existing array and remove some items from array copy without impacting the original. I've tried this :</p>
  
  <pre><code>var new_arr = old_arr; //when I remove from new array the items from old array are also removed
  </code></pre>
  
  <p>How do I create entirely new copy of the existing array?</p>
  
  <p><strong>Update :</strong></p>
  
  <p>When I do this :</p>
  
  <pre><code>var new_arr = old_arr.slice();
  </code></pre>
  
  <p>then later :</p>
  
  <pre><code>new_arr[0].shift();
  new_arr[1].shift();
  </code></pre>
  
  <p>The items from old_array get removed. This is a two dimensional array.</p>