title: Handling "undefined" JSON values in jqGrid
body: <p>In my JSON, sometimes I don't return a value for a column -- I simply omit that column from the JSON.  In this case, I would like these cells in the grid to be empty.</p>
  
  <p>However, this causes display issues in jqGrid.  The values of these cells become <code>undefined</code>.</p>
  
  <p>Is there a solution to this other than adding the empty columns to the JSON as empty strings or creating a formatter function in the <code>colModel</code> that checks for <code>undefined</code>?</p>
  
  <p>Thanks!</p>