计算不包含某个类的元素

Question

如何计算没有类.extra？

的元素.em

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var cnt = $('.em').not('.extra').length;
console.log(cnt);

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<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="em">
  <div class="header">aaa</div>
  <ul>nnn</ul>
</div>

<div class="em">
  <div class="header">aaa</div>
  <div class="extra">eee</div>
  <ul>nnn</ul>
</div>

<div class="em">
  <div class="header">aaa</div>
  <ul>nnn</ul>
</div>

＆＃13;

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Answer 1

您使用.em类来否定.extra个元素。由于.em元素都没有类.extra，因此所有元素都被选中。

一种选择是将:not()与:has() selector合并：.em:not(:has(.extra))

＆＃13;

＆＃13;

var cnt = $('.em:not(:has(.extra))').length;
console.log(cnt);

＆＃13;

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="em">
  <div class="header">aaa</div>
  <ul>nnn</ul>
</div>

<div class="em">
  <div class="header">aaa</div>
  <div class="extra">eee</div>
  <ul>nnn</ul>
</div>

<div class="em">
  <div class="header">aaa</div>
  <ul>nnn</ul>
</div>

＆＃13;

＆＃13;

＆＃13;