如何检测 bootstrap card-header 在打字稿中悬停？

Question

我在 bootstrap 中有一张卡片，在 header 中有一个按钮，我想仅当用户将鼠标悬停在 header 上时才显示该按钮，有些东西喜欢： ngIf="card-heaver.hoverover"。所以我需要检测悬停在 html 或打字稿一侧。

Answer 1

出于性能等多种原因，您不想那样做，而是像这样将这些东西保留在表示层和合成器线程上；

.card-header > .btn {
  opacity: 0;
  transition: opacity .35s ease;
}

.card-header:hover > .btn {
  opacity: 1;
}

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>


<div class="card">
  <div class="card-header">
    Quote <button class="btn btn-sm btn-primary">Button</button>
  </div>
  <div class="card-body">
    <blockquote class="blockquote mb-0">
      <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p>
      <footer class="blockquote-footer">Someone famous in <cite title="Source Title">Source Title</cite></footer>
    </blockquote>
  </div>
</div>

周末愉快，干杯！

如何检测 bootstrap card-header 在打字稿中悬停？

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