Rich Text.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>Rich Text</title>
    <style>
      html,
      body {
        margin: 0;
        padding: 0;
      }

      iframe,
      div {
        width: 100vmin;
        height: 50vmin;
        border: 1px solid black;
        box-sizing: border-box;
      }
    </style>
  </head>

  <body>
    <iframe
      src="./resource/ifame.html"
      frameborder="0"
      id="richEdit"
      name="richedit"
    ></iframe>
    <div contenteditable="true"></div>
  </body>
  <script>
    var iframeEle = document.getElementById('richEdit');
    iframeEle.contentDocument.contentEditable = true;
    iframeEle.contentDocument.designMode = 'on';
    /*
        对文档执行预定义的命令
        document.execCommand("命令名称"，"为当前命令提供用户界面的布尔值"，"执行命令必须的一个值")
        为保证浏览器兼容性，第二个参数应当始终为 false
    */
    console.log('to be continued...');
  </script>
</html>