帮帮忙，看看这个function该怎么写？

[happy2003]

要求三个单元格都必须填；并且“值”界于（0，1）;累计必须为1）
，同时表格下加一行

[happy2003]

就象csdn那样？

[lgchao]

function chk(n1,n2,n3)
{
if(n1+n2+n3!=1) return false;
if(n1<=0 || n1>=1) return false;
if(n2<=0 || n2>=1) return false;
if(n3<=0 || n3>=1) return false;
return true;
}

[genuis]

<script language="javascript">
var cen = document.all.pop;
function fen()
{
var zhong = parseInt(document.all.zhongFen.value); //得到总分值
var a = document.getElementsByName("T");
var gei = 0;
for (var i=0; i<a.length; i++)
{ gei = (a[i].value=="") ? gei : (gei + parseInt(a[i].value));}
var n = zhong-gei;
cen.style.background = (n < 0) ? "#FF0000" : "#FFFF00";
cen.innerText = "该问题总分值："+ zhong +"\r\n现可给的分值："+ n;
return n;
}
function cc(e)
{
if (e.name != "T") return;
e.select();
fen();
/*
var ttop = e.offsetTop; //TT控件的定位点高
var thei = e.clientHeight; //TT控件本身的高
//var tleft = e.offsetLeft; //TT控件的定位点宽
while (e = e.offsetParent){ttop += e.offsetTop; tleft += e.offsetLeft;}
cen.style.top = ttop+thei+4; //层的 Y 坐标
//cen.style.left = tleft + 1; //层的 X 坐标

var tleft = e.offsetLeft;
while (e = e.offsetParent){ttop += e.offsetTop; tleft += e.offsetLeft;}
cen.style.left = tleft + e.clientWidth - cen.clientWidth;
*/
var ttop = e.offsetTop;
var tleft= e.offsetLeft;
var h = e.clientHeight; //在下面这个 while 循环里的e已经不是那个形参了
var w = e.clientWidth;

while (e = e.offsetParent){ttop += e.offsetTop; tleft += e.offsetLeft;}
cen.style.display = ""; //层显示
cen.style.top = ttop + h;
cen.style.left= tleft + w - cen.clientWidth;

}
function out(){cen.style.display = "none";}
function check(e)
{
var k = window.event.keyCode;
if (k < 48 || k > 57){
alert("你输入的不是数字！")
window.event.keyCode = 0 ;}
}
</script>

这是csdn的代码

[happy2003]

谢谢大家！