html自适应怎么没有滚动条（如何让pre和textarea等HTML元素去掉滚动条自动换行自适应文本内容高度）

<pre>ourjs this is very very very very very very very very very very very very very very very logn contents.</pre>
pre {
    word-wrap: break-word;
    white-space: pre-wrap;

    padding: 9.5px;
    background-color: #f5f5f5;
    border: 1px solid #ccc;
}

var textarea = document.getElementsByTagName('textarea')[0];
textarea.setAttribute('style','height:'+(textarea.scrollHeight + 12)+'px');