title: document.elementById returns null after jQuery loads external content with .load() or .post()
body: <p>I am using jQuery to load some data inside a div, after posting some options. The returned data also contains a dynamically generated form. After the data has loaded, I need to get the form values using getElementById(name), but it does not work (returns null).</p>
  
  <p>I have tried sending and loading the results with .load() and .post()</p>
  
  <p>Example code:</p>
  
  <pre><code>//function to load data
  function loadProductPrices(var1)
  {
      //#thisProductPrices is the data container
      $('#thisProductPrices').load('filename.php', { 'var1': var1});
  }
  
  //function to get element value after previous function has been called 
  //(this one is called by a button that is part of the content that has 
  //been generated by the previous call) 
  function getAndSaveValue(elementID)
  {
      var thisValue = document.getElementById(elementID).value; // this returns null (?)
      // after I have the new value I will post and save, using jquery again.
  }
  </code></pre>
  
  <p>The html generated by loadProductPrices() returns a list of items</p>
  
  <pre><code>PriceValue
  &lt;input type="text" id="price_productID" value="PriceValue" /&gt;
  &lt;input type="button" value="save new price" onclick="getAndSaveValue(price_productID)" /&gt;
  // the above button calls getAndSaveValue, in order to retrieve the new price 
  //and save it...
  //however it returns null.
  </code></pre>
  
  <p>Any suggestions? thnx!</p>