为第一个项目元素添加活动类

Question

为第一个项目元素添加活动类

ani*_*css 2 javascript jquery twitter-bootstrap

<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
  
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
</head>
<body>
	<div id="carousel-example-generic" class="carousel slide" data-ride="carousel">
  <!-- Indicators -->
  <ol class="carousel-indicators">
    <li data-target="#carousel-example-generic" data-slide-to="0" class="active"></li>
    <li data-target="#carousel-example-generic" data-slide-to="1"></li>
    <li data-target="#carousel-example-generic" data-slide-to="2"></li>
  </ol>

  <!-- Wrapper for slides -->
  <div class="carousel-inner" role="listbox">
    <div class="item active">
      <img src="http://ichef.bbci.co.uk/news/976/cpsprodpb/87D3/production/_84817743_beckhamfashion.jpg" alt="...">
      <div class="carousel-caption">
        ...
      </div>
    </div>
    <div class="item">
      <img src="http://ichef.bbci.co.uk/news/976/cpsprodpb/9949/production/_84814293_dummy.jpg" alt="...">
      <div class="carousel-caption">
        ...
      </div>
    </div>
    ...
  </div>

  <!-- Controls -->
  <a class="left carousel-control" href="#carousel-example-generic" role="button" data-slide="prev">
    <span class="glyphicon glyphicon-chevron-left" aria-hidden="true"></span>
    <span class="sr-only">Previous</span>
  </a>
  <a class="right carousel-control" href="#carousel-example-generic" role="button" data-slide="next">
    <span class="glyphicon glyphicon-chevron-right" aria-hidden="true"></span>
    <span class="sr-only">Next</span>
  </a>
</div>
  
  
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>

<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>
</body>
</html>

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例如，我正在使用 bootstap carousel；

<div id="carousel-example-generic" class="carousel slide" data-ride="carousel">

  <div class="carousel-inner" role="listbox">

    <div class="item active">
      <img src="..." alt="...">
      <div class="carousel-caption">

      </div>
    </div>

    <div class="item">
      <img src="..." alt="...">
      <div class="carousel-caption">
        ...
      </div>
    </div>

  </div>

  <!-- Controls -->
  <a class="left carousel-control" href="#carousel-example-generic" role="button" data-slide="prev">
    <span class="glyphicon glyphicon-chevron-left" aria-hidden="true"></span>
    <span class="sr-only">Previous</span>
  </a>
  <a class="right carousel-control" href="#carousel-example-generic" role="button" data-slide="next">
    <span class="glyphicon glyphicon-chevron-right" aria-hidden="true"></span>
    <span class="sr-only">Next</span>
  </a>
</div>

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正如你看到的，我的第一个.item类有.active类，但是当我.active从.item类中删除类时我想自动添加它然后 javascript 给了我这个错误：TypeError: Cannot read property 'offsetWidth' of undefined /works/anitur/js/bootstrap.min.js:6我试图用这个代码添加

$(".carousel > .item:first").addClass("active");

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但没有任何改变我怎么能意识到我想要什么？顺便说一句，有没有办法用js而不是html添加轮播控件？

Answer 1

Jam*_*mes 5

更好的做法是在 HTML 模板本身中为轮播添加类。为什么因为轮播插件会在document is ready. 不过你可以试试下面的代码。

$(".carousel .item").first().addClass("active");

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