使用相同的类jquery计算元素的数量

Question

我有一个ul元素.现在我想知道有多少li人selected上课了.

<ul class="icon-list icon-list-inline star-rating" id="star-rating">

        <li class="selected"></li>
        <li class=""></li>
        <li class=""></li>
        <li class=""></li>
        <li class=""></li>
</ul>


var vote_selected = $('#star-rating ... ???').length;

它必须返回1.

Answer 1

使用子选择器与类:

var vote_selected = $('#star-rating > .selected').length;

alert(vote_selected);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<ul class="icon-list icon-list-inline star-rating" id="star-rating">
  <li class="selected"></li>
  <li class=""></li>
  <li class=""></li>
  <li class="selected"></li>
  <li class=""></li>
</ul>

Answer 2

尝试这个 ：-

var vote_selected = $('#star-rating li[class="selected"]').length;

演示

或（可以使用的li直接后代）。#star-rating>

var vote_selected = $('#star-rating > li[class="selected"]').length;

要么

var vote_selected = $('#star-rating > .selected').length;