title: Checking if an element exists in json
body: <p>using the following feed:</p>
  
  <p><a href="http://api.twitter.com/1/statuses/user_timeline.json?screen_name=microsoft&amp;include_rts=1&amp;count=10">http://api.twitter.com/1/statuses/user_timeline.json?screen_name=microsoft&amp;include_rts=1&amp;count=10</a></p>
  
  <p>I am successfully able to loop through this to get the details I want to display on my html page.</p>
  
  <p>However, I need to check if <code>retweeted_status.user.profile_image_url</code> exists, and I am not sure how to do that?</p>
  
  <p>Currently I am looping through the data where <code>data</code> is returned by jquery-ajax:</p>
  
  <p><code>data[i].retweeted_status.user.profile_image_url</code></p>
  
  <p>if <code>data[i].retweeted_status.user.profile_image_url</code> does not exist, it does not return null or undefined, I just get the following error:</p>
  
  <p><code>cannot read property 'user' of undefined</code></p>