title: Traverse through Javascript object properties
body: <p>I want to traverse through JavaScript object's property</p>
  <pre><code>var obj =
  {
      a: 'value1',
      b: 'value2',
      c: 'value3',
      d: 'value4'
  };
  
  for (var prop in obj) {
      prop = 'xxx';
  }
  </code></pre>
  <p>But the above code is not working. Can you help me how to do so ?</p>