title: Json - checking child node null value
body: <p>How can i check if a child attribute of a json object is null? While firefox recognizes it, Chrome and IE 8 don't.</p>
  
  <p>I have a json object like this:</p>
  
  <pre><code>centralData.phone.id;
  centralData.address.id;
  centralData.product.id;
  //and many others
  </code></pre>
  
  <p>And i'd like to check if some of it's attributes might be null. I'm doing this and it works:</p>
  
  <pre><code>if(centralData.phone != null){
     //Do things
  }
  </code></pre>
  
  <p>But this don't, since it's not always i have a StockGroup</p>
  
  <pre><code>if(centralData.product.StockGroup != null){
   //Error
  }
  </code></pre>
  
  <p><strong>So, how can i check if <code>centralData.product.StockGroup</code>  is null?</strong></p>