jQuery Grid Plugin - jqGrid

I want to pass zero if my text box is empty or pass the value if user enter a value the text box

I use following code to pass which works without if statement

 

 jQuery("#MyGrid").jqGrid('setGridParam',{url: "../MyServer.cfc?method=MyMethod&StartDate="
   +jQuery("#dtpStartDate").val()+"&EndDate="
   +jQuery("#dtpEndDate").val()+"&MyNumber="
   +jQuery("#Mytxt").val()}).trigger("reloadGrid")

 

 

I just added if stament like following code, but it fails

 

 jQuery("#MyGrid").jqGrid('setGridParam',{url: "../MyServer.cfc?method=MyMethod&StartDate="
   +jQuery("#dtpStartDate").val()+"&EndDate="
   +jQuery("#dtpEndDate").val()+"&MyNumber="
   +if(jQuery("#Mytxt").val().length == 0)
                   {0}
                 Else
                {jQuery("#Mytxt").val()}).trigger("reloadGrid")

 

 

I would like to learn how I can pass parameter base on user entry or not,

Your help and information is great appreciated,