使用 contenteditable="true" 实现的文本框全选内容![image.png](https://p9-

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    /* 输入框 */
    #dzm-textarea {
      padding: 5px;
      border: 1px solid red;
    }
    /* 输入框为空时显示 placeholder */
    #dzm-textarea:empty:before {
      content: attr(placeholder);
      color: red;
    }
    /* 输入框获取焦点时移除 placeholder */
    #dzm-textarea:focus:before {
      content: none;
    }
  </style>
</head>
<body>
  <!-- textarea -->
  <div id="dzm-textarea" class="dzm-textarea" contenteditable="true" placeholder="请输入内容" style="resize: both; overflow: auto;">
    <!-- 内部内容 -->
    <div>dzm-text</div>
  </div>
  <script>
    // 调用
    select('dzm-textarea')
    // 自定义文本框全选内容
    function select(id) {
      if (document.selection) {
        var range = document.body.createTextRange()
        range.moveToElementText(document.getElementById(id))
        range.select();
      } else if (window.getSelection) {
        var range = document.createRange()
        range.selectNodeContents(document.getElementById(id))
        window.getSelection().removeAllRanges()
        window.getSelection().addRange(range)
      }
    }
  </script>
</body>
</html>