用一个div模拟textarea的实现

<div class="textarea" contenteditable="true">输入文字</div>

.textarea{
  resize: both;
  min-width: 300px;
  min-height: 100px;
  padding: 5px;
  border: 1px solid #ccc;
  border-radius:5px;
  line-height: 1.2;
  outline:none;
  overflow:auto;
}