js动态添加classname

js动态添加classname ?
今天无疑在qq拍拍源码上看到一串这样的代码可以动态添加classname觉得不错就抄了下来

<script type="text/javascript">window.onload = function () { var ulBox = document.getElementById("content"); var list = ulBox.getElementsByTagName("li"); for (var i=0; i<list.length; i++) {  list[i].onmouseover=function() {   this.className="hover";  }  list[i].onmouseout=function() {   this.className="";  } }}</script>

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