css与dom的渲染与解析

js阻塞文档渲染与解析那么css呢？

结论一、css：阻塞渲染，不阻塞dom解析

<head>
      <script>
        document.addEventListener('DOMContentLoaded',function(){
            alert(document.getElementById("myinput"))
        })
    </script>
<!--    <script src="http://libs.baidu.com/jquery/2.1.4/jquery.min.js"></script>-->

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
</head>

<body>
    <input type="text" id="myinput" />
<span class="label label-default">Default</span>
</body>

当css样式还未加载完成的时候，初始的html文档已经加载，解析完毕了

结论二、css的加载阻塞后面加载

<head>
      <!--<script>
        document.addEventListener('DOMContentLoaded',function(){
            alert(document.getElementById("myinput"))
        })
    </script>-->
  <script src="http://libs.baidu.com/jquery/2.1.4/jquery.min.js"></script>

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<script>
    alert(1)
</script>
</head>

<body>
    <input type="text" id="myinput" />
<span class="label label-default">Default</span>
</body>

由于js的性值，加载后立即执行，可以判断，css阻塞js的加载

posted on 2018-11-01 14:53 爬虫一只阅读(309) 评论(0) 收藏举报