Updating A Unique Field

[bookish]

Happy new year! Could someone help me in this script? I am trying to edit a unique field in an update form. It allows me to edit f I select a text field. But to prevent the user from making a mistake, i enclosed the field in 2 html blocks 

<table style="display:none;">

</table>

 

I place this script in the footer. It does show the right answer {(I tested using document.write(res)] and confirmation email is sent, but the unique field is not changed. 

 

<SCRIPT LANGUAGE="JavaScript">

var str = "[@field:combined_ID]"
var res = str.slice(0,16);
document.getElementById("InsertRecordcombined_ID").value = res;

</script>

 

Thanks in advance.

[MayMusic]

If it is an update for you should change document.getElementById("InsertRecordcombined_ID").value = res; to document.getElementById("EditRecordcombined_ID").value = res;