原生JS操作元素类名的完整指南

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title></title>
    <style type="text/css" media="screen">
      #box {
        width: 200px;
        height: 200px;
        margin: 0 auto;
        background: pink;
        border-radius: 20px;
      }
      @keyframes move{
        0%{width: 500px; background-color: red;}
        10%{width: 100px; background-color: green;},
        20%{width: 900px; background-color: yellow;},
        50%{width: 300px; background-color: pink;},
        80%{width: 550px; background-color: gold;},
        100%{width: 200px; background-color: purple;}
      }
      .movea {
        animation: move 1s ;
      }
    </style>
  </head>
  <body>
    <div id='box'>
    </div>
  <script type="text/javascript">
    document.getElementById('box').onclick = function() {
      this.setAttribute("class", "movea");
      this.classList.add("movea");
    }
  </script>
  </body>
</html>

var dom = document.getElementById("idName");

dom.classList.add("className1");

dom.classList.add("className1", "className2", "className3", ....., "classNameN");

dom.classList.remove("className1");

dom.classList.remove("className1", "className2", "className3", ....., "classNameN");

dom.classList.contains('className'); //return true or false