[Vtigercrm-developers] How to detect field value change on Edit View Save?

[Alan Lord]

I have a custom "validation" function. This is an ajax routine.

In Detail View (and Summary) I can stop the default event 
"PreAjaxSaveEvent", perform my checks and do what is necessary.

In Edit View though I am struggling to determine if a field has had its 
value altered before the user clicks the save button. I can trap the 
event "Vtiger_Edit_Js.recordPresaveEvent" OK but is there any way I can 
determine if a field's value has changed or not?

TIA

Al