为了填充初始页面的数据，我写了2个js函数，一个设置表单默认值，一个自动点击按钮以计算结果，但是两个函数同时放到onload后面就出错了，不知道问题出在哪里，请帮忙看看，
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<script type="text/javascript">
function setval(){
var gd = document.getElementById("gaodu").value;
var kd = document.getElementById("kuandu").value;
var sl = document.getElementById("shuliang").value;
if(gd=="")
document.getElementById("gaodu").value=1600;
if(kd=="")
document.getElementById("kuandu").value=600;
if(sl=="")
document.getElementById("shuliang").value=1;
}
function danji(){
document.getElementById("sub").click();
}
</script>
</head>
<?php
$gaodu=$_GET["gaodu"];
$kuandu=$_GET["kuandu"];
$shuliang=$_GET["shuliang"];
?>
<body onload="setval();danji()">
<form action="">
<input name="gaodu" id="gaodu" type="text" value="<?php echo $gaodu ?>">
<input name="kuandu" id="kuandu" type="text" value="<?php echo $kuandu ?>">
<input name="shuliang" id="shuliang" type="text" value="<?php echo $shuliang ?>">
<input name="sub" id="sub" type="submit" value="计算">
</form>
<table width="200" border="1">
<tr>
<td><?php echo $gaodu+$kuandu ?></td>
</tr>
</table>
</body>
</html>
