请教：如何更改td的class？

Question

<td class="td1" onmouseover="this.class='newclass'">

Answer 1

<td class="td1" onmouseover="this.className='newclass'">

Answer 2

<td class="td1" onmouseover="this.class='newclass'">
我也是这么写的，不过失败了----------------------------------------------------------------------------------<td class="td1" onmouseover="this.className='newclass'">
测试通过，谢谢