I have users who have not been completing all required data.
<cfset unloadCheck=0>//a ColdFusion precheck in my page generation to see if unload check is needed
var erMsg="";
$(document).ready(function(){
<cfif q.myData eq "">
<cfset unloadCheck=1>
$("#myInput").change(function(){
verify(); //function elsewhere that checks all fields and populates erMsg with error messages for any fail(s)
if(erMsg=="") window.onbeforeunload = null; //all OK so let them pass
else window.onbeforeunload = confirmExit(); //borrowed from Jantimon above;
});
});
<cfif unloadCheck><!--- if any are outstanding, set the error message and the unload alert --->
verify();
window.onbeforeunload = confirmExit;
function confirmExit() {return "Data is incomplete for this Case:"+erMsg;}
</cfif>