这与不可能textarea。您正在寻找的是一个内容可编辑的 div，这很容易做到：

<div contenteditable="true"></div>






div.editable {

    width: 300px;

    height: 200px;

    border: 1px solid #ccc;

    padding: 5px;

}



strong {

  font-weight: bold;

}


<div contenteditable="true">This is the first line.<br>

See, how the text fits here, also if<br>there is a <strong>linebreak</strong> at the end?

<br>It works nicely.

<br>

<br><span style="color: lightgreen">Great</span>.

</div>