title: clear values in jqgrid post parameter array
body: <p>I'm going to simplify this question. </p>
  
  <p>I have a jqgrid instance which posts an array of ids to the server. I would like the pass in a new list when an event is triggered. Instead of overwriting the old list, jqgrid will add to it. How can i set the post parameters to create a new list each time I reload the grid. </p>
  
  <p>This is the code to reload the grid with new post data</p>
  
  <pre><code>  $('#gridConfirm').jqGrid('setGridParam',{postData:{'deviceIDs':$("#device").val()}});
    $('#gridConfirm').trigger('reloadGrid');
  </code></pre>
  
  <p>I've confirmed that $("#device").val() returns a list of id's in the form "5,6,7,8"; So i'm expecting this list to be posted to the server. </p>
  
  <p>Instead, its posting "5,6,7,8" plus the previous list. so if the previous list was "1,2,3,4". It's posting "5,6,7,8,1,2,3,4"</p>
  
  <p>How can i clear the previous posted list when reloading the grid?</p>
  
  <p>*<strong><em>edit</em>*</strong>
  On slight correction, when i change my postdata list. It does not append it overwrites, but it keeps the length of the list. </p>
  
  <p>so if my original list was 1,2,3,4,5 and i selected 6,7 my new list is 6,7,3,4,5</p>
  
  <p>I'm thinking this is a bug in the grid. </p>