jQuery中的on()和click()的区别

<p>
 <h1>Click</h1>
 <button class="add">Click me to add new item</button>
 <ul class="li">
 <li>I am old item.<button class="delete">Delete</button></li>
 <li>I am old item.<button class="delete">Delete</button></li>
 <li>I am old item.<button class="delete">Delete</button></li>
 </ul>
</p>

<script type="text/javascript" src="jquery-1.8.3.min.js"></script>
<script type="text/javascript">
$(".add").click(function(){
 $(".li").append('<li>I am new item.<button class="delete">Delete</button></li>');
});
$(".delete").click(function(){
 $(this).parent().remove();
});
</script>

$(".li").on('click','.delete',function(){
 $(this).parent().remove();
});