<!DOCTYPE html>
<html>
<head>
<script src="/lib/jquery-1.12.2.min.js"></script>
<script>
$(document).ready(function(){
$("input").change(function(){
alert("The text has been changed.");
});
});
</script>
</head>
<body>
<input type="text">
<p>Write something in the input field, and then press enter or click outside the field.</p>
</body>
</html>