How to get the element number/index between siblin

问题:

This question already has an answer here:

• Determining child index in it's parent [duplicate] 1 answer

How can you get the child number of the selected element, e.g.

<ul>
    <li>First child</li>
    <li>Second</li>
    <li id="selected">Third child</li>
    <li>Fourth child</li>
</ul>

Using something like this:

$('#selected').childNumber();

That should return "3" for it's parent wrap, regarding the child number.

回答1:

You can use .index() for this.

var selectedIndex = $("#selected").index() + 1;

Since you have given an id for the li there is no need for the element selector with ul. You can directly use the id selector for the li element.