on method in jquery

The issue for people picking up jQuery is that the on() method can be pretty overwhelming, especially at the beginning. Because it does the job of a lot of other methods, it comes across as fairly complex.

Example

<!DOCTYPE html>
<html>
<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js">
</script>
</head>
<body>
	<div>Click me</div>
	<script>
$("div").click(function() {
alert("from click hello");
});
// instead of using click we use on ithwith event name as below
$("div").on("click", function() {
alert("from on hello");
});
</script>
</body>
</html>

Instead of using individual methods for all the different events, you pass the event name in as the first parameter and then the event handler in as the second.
 
The reason for this change was simple: previously there were a huge number of methods, all focused on event binding. There were individual event handlers like click(), hover(), and so on. Then there were more methods for general event binding, such as bind(), live(), and delegate().