将部分jquery替换成javascript——进度条加载

Question

我想替换代码“$('body').addClass('noscroll');”进入 vanilla javascript，我尝试了不同的解决方案，但它不起作用。

谢谢！

$(document).ready(function() {
 $('button').click(function(){
      
        //$('body').addClass('noscroll');
      
        var el = document.getElementsByTagName('body');

        el.className = "noscroll";      
      
        document.querySelector("#overlay").classList.remove('is-visible');
 });
});

#overlay {
  background: #ffffff;
  color: #666666;
  position: fixed;
  height: 100%;
  width: 100%;
  z-index: 5000;
  top: 0;
  left: 0;
  float: left;
  text-align: center;
  padding-top: 25%;
  opacity: .80;
}

button {
  margin: 40px;
  padding: 5px 20px;
  cursor: pointer;
}
.spinner {
    margin: 0 auto;
    height: 64px;
    width: 64px;
    animation: rotate 0.8s infinite linear;
    border: 5px solid firebrick;
    border-right-color: transparent;
    border-radius: 50%;
}


@keyframes rotate {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}


.is-visible {
 display: none;
}


.noscroll {
  overflow: hidden;
}

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<script src="https://code.jquery.com/jquery-3.1.0.js"></script>

<body>

</br>
</br>
</br>
</br>
</br>
</br>
</br>

  <button>Load Spinner</button>

<div id="overlay" class="is-visible">
    <div class="spinner"></div>
    <br/>
    Loading...
</div>

</br>
</br>
</br>
</br>
</br>
</br>
</br>
</br>
</br>
</br>
</br>
</br>
</br>
</br>
</br>
</br>
</br>
</br></br>
</br></br>
'lllk
</br></br>
</br>
</body>
</html>

Answer 1

body 是 document 的一部分，所以

添加一个class

document.body.classList.add('noscroll');

并删除它

document.body.classList.remove('noscroll');

将部分jquery替换成javascript——进度条加载

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progress-bar