Get hours difference from Date/Time field with current Date/Time

Hi,

I'm trying to get the difference between field Date/Time with current Date/Time.

If the difference is less than 3 hours, then, a message will be displayed. My problem is that I can't get the difference in hours (I got a number and can't be change to date using StringToDate)...

I used this code:

   var locked_Time = nlapiGetFieldValue('custbody_locked_time');   locked_Time = nlapiStringToDate(locked_Time);   var Now = new Date();   Now = nlapiStringToDate(Now);   var difference = Now - locked_Time;    //following code not tested yet, since I've still can't get the value for the difference, but I added it to explain my code and what I want to do.  If (difference < 3)  {  var html = '<script language="JavaScript" type="text/javascript">';              html += 'alert("This record in edit mode by another user")';              html += '</script>';              var htmlField = form.addField('custpage_alert', 'inlinehtml', 'This record in edit mode by another user' ,null,null);             htmlField.setDefaultValue(html);  }