Get it through window.location.href method.
$('#wadonedeal').click(function(){
var whatsAppPhone = '<?php echo $agentDet['contact']; ?>';
var defaultMessage = "Hi, found you on";
window.open(
"https://wa.me/"+'+60'+whatsAppPhone+"?text="+defaultMessage+" "+window.location.href,
'_blank',
);
});