js模拟键盘事件

<!DOCTYPE html>
<html>
<head lang="zh-CN">
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1"/>
 <title></title>
 <style>
     .button {
          200px;
         height: 200px;
         background-color: antiquewhite;
         margin: 20px;
         text-align: center;
         line-height: 200px;
     }
 </style>
</head>
<body>
 <div class="button">Button</div>
 <script>
     "use strict";
     var btn = document.querySelector('.button');
     document.addEventListener('keyup', function (event) {
         console.log(String.fromCharCode(event.keyCode));
     }, false);
     var ev = new KeyboardEvent('keyup', {
         keyCode: 65
     });
     document.dispatchEvent(ev);
 </script>
</body>
</html>