title: How to delete a value of an object inside of an array
body: <p>How come this isn't working? Everything seems right to me. Am I missing something?</p>
  <p>Write a function called removePartyKillers that takes in an array like &quot;playlist&quot;
  (see below) and returns a copy of that playlist where any song longer than 8 minutes
  has been removed. You can safely assume that a playlist is an array of objects.
  Each object will have the properties title, artist, and durationInSeconds.</p>
  <pre><code>var awesomePlaylist = [
    {
      title: &quot;Hay Day&quot;,
      artist: &quot;Robo-Crop&quot;,
      durationInSeconds: 378
    }, {
      title: &quot;10,000 Pounds&quot;,
      artist: &quot;L-Ton Jonn&quot;,
      durationInSeconds: 498,
    }, {
      title: &quot;Caesar's Salad&quot;,
      artist: &quot;DJ Dinner Julius&quot;,
      durationInSeconds: 600,
    }, {
      title: &quot;The British Are On Their Way&quot;,
      artist: &quot;Raul Pevere&quot;,
      durationInSeconds: 1095,
    }, {
      title: &quot;13th&quot;,
      artist: &quot;The Doctors&quot;,
      durationInSeconds: 185,
    }
  ];
  
  function removePartyKillers(arr) {
      var copy = arr.slice();
      for (var key of copy) {
          for (var key2 in key) {
              if (key2['durationInSeconds'] &gt; (60 * 8)) {
                  delete key2;
              }
          }
      }
      return copy;
  }
  
  console.log(removePartyKillers(awesomePlaylist));
   /* Results:
    {
      title: &quot;Hay Day&quot;,
      artist: &quot;Robo-Crop&quot;,
      durationInSeconds: 378
    }, {
      title: &quot;13th&quot;,
      artist: &quot;The Doctors&quot;,
      durationInSeconds: 185,
    }
  ]
  */ 
  </code></pre>