title: Internet Explorer Javascript syntax error
body: <p>I work on web site with pre-existent javascript syntax error.</p>
  
  <p>I found in a page a JSON object like this</p>
  
  <pre><code>var obj = { prop1: 1, prop2: 2, prop3: 3,};
  </code></pre>
  
  <p>obviously the error is the last comma in object property definition.</p>
  
  <p>While i was debugging my code there were no error reported by Chrome, Opera, Firefox or IE.
  All javascript code works fine.</p>
  
  <p>The error was generated only in same IE browser of the website users.</p>
  
  <p>Is there any way to set browser to show error like this?</p>