js清空table，急！在线等！

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<html>

<head>

<script type="text/javascript">

function contactlist(){

		var table = document.getElementById("contactTable");

		var tr = table.insertRow(table.rows.length);//添加一行

		tr.align="center";

		tr.bgcolor="#F3F4F3";

		tr.height="23";



		//添加五列

		var td0 = tr.insertCell(0);

		td0.width="20%";

		var td1 = tr.insertCell(1);

		td1.width="20%";

		var td2 = tr.insertCell(2);

		td2.width="8%";

		var td3 = tr.insertCell(3);

		td3.width="30%";

		var td4 = tr.insertCell(4);

		td4.width="20%";

		

		//设置列内容

		td0.innerHTML = "";

		td1.innerHTML = "<input type='file' id='dataAudio' name='dataAudio'/><input type='hidden' name='dataAudios'/><input type='hidden' name='audioOldName'/>";

		td2.innerHTML = "<input type='text' name='playDateTime' id='playDateTime' onkeyup='validateNumber(this);' size='5' maxlength='3' style='color: red' />";

		td3.innerHTML = "<input type='text' name='content' id='content' size='35' maxlength='300'/>";

		td4.innerHTML = "<input type='button' value='删除' onclick='removeRow(this.parentNode.parentNode)'/>";

		

	}



function removeRow(r)

{

    var root = r.parentNode;

    var allRows = root.getElementsByTagName('tr');

    if(allRows.length > 3){

        root.removeChild(r);

    }else{

    	alert("不能删除改行！");

    }

}

</script >

</head>





<body>



<table id="contactTable" width="98%" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#D9D9D9"> 

	    <tr bgcolor="#F3F4F3" align="center" height="23">

	       <td colspan="5" align="left"><input type="button" value="添加帧" class="button" onclick="return contactlist();"/></td>

	    </tr>

	    <tr bgcolor="#F3F4F3" align="center" height="23">

	       <td width="20%">上传图片</td>

	       <td width="20%">上传声音</td>

	       <td width="8%">播放时间</td>

	       <td width="30%">内    容</td>

	       <td width="20%">操作</td>

	    </tr>

	</table>



</body>

</html>