Usage analysis of index() in jQuery_jquery

This article explains the usage of index() in jQuery with examples. Share it with everyone for your reference. The specific method is as follows:

Now I have a question: If there are N number of list items in the list, I want to know which one I clicked and how to retrieve it?

For this, jQuery provides an index() method:

index(subject)

This method searches for elements matching the object represented by the parameter and returns the index value of the corresponding element.

If a matching element is found, the return starts from 0; if no matching element is found, -1 is returned.

But the examples provided in the API seem wrong. The examples are as follows:

<ul>
  <li><a href="#nogo">这里是一个序列</a></li>
  <li><a href="#nogo">这里是一个序列</a></li>
  <li><a href="#nogo">这里是一个序列</a></li>
  <li><a href="#nogo">这里是一个序列</a></li>
  <li><a href="#nogo">这里是一个序列</a></li>
  <li><a href="#nogo">这里是一个序列</a></li>
</ul> 

As shown above, this is an unordered list. What if I want to click on any list item and get the sequence of the item?

The implementation method is as follows:

$(document).ready(function(){ 
$("#act li").click(function(){
  alert( $( "#act li" ).index( $(this)[0] ) );
  })
}) 

Here:

$( "#act li" ).index( $(this)[0] )

Very important!