如何动态获取Select菜单中的value值

[shidabbs]

Html代码如下:
<form id="PointForm" name="PointForm" method="post" action="SaveTo.asp">
<select name="User5Point1" id="User5Point1" onchange="Recount(5);">
<option value="10">10</option>
<option value="9">9</option>
</select>
<select name="User5Point2" id="User5Point2" onchange="Recount(5);">
<option value="10">10</option>
<option value="9">9</option>
</select>
<span id="PointResult5">10</span>
</form>

现在我需要在Javascript中获取多个类似的select 的值
<script>
function Recount(UserId){
var count=0;

myPoint1 = eval("User"+UserId+"Point1");
myPoint2 = eval("User"+UserId+"Point2");
myPointResult = eval("PointResult"+UserId);
count+=myPoint1.options[myPoint1.selectedIndex].value*.8;
count+=myPoint2.options[myPoint2.selectedIndex].value*.2;
count=Math.round(count*10)/10
myPointResult.innerHTML=count;
}
</script>
我的这段代码无法正常运行,谁能告诉我错在哪里,应该怎么做

[Go 旅城通票]

function Recount(UserId){ 
var count=0; 

myPoint1 = eval("User"+UserId+"Point1"); 
myPoint2 = eval("User"+UserId+"Point2"); 
myPointResult = eval("PointResult"+UserId); 
count+=parseInt(myPoint1.options[myPoint1.selectedIndex].value*.8); //
count+=parseInt(myPoint2.options[myPoint2.selectedIndex].value*.2); //
count=Math.round(count*10)/10 
myPointResult.innerHTML=count; 
} 

[wentimao]

错在eval这里，如果对象直接在body下，这样写没错，但在from中了，你就不可以这样写了 你可以通过document.getElementById("User"+UserId+"Point1")获得;

[wentimao]

补充一下 ，这样写也者可以，这是根据name走的
myPoint1 = eval("document.forms[0]['User"+UserId+"Point1']");
myPoint2 = eval("document.forms[0]['User"+UserId+"Point2']");
myPoint1=document.forms[0]["User5Point1"];
myPoint2=document.forms[0]["User5Point2"];

[ximizhi]

myPoint1 = document.getElementById("User"+UserId+"Point1");
myPoint2 = document.getElementById("User"+UserId+"Point2");