如果用javascript如何把长的数字用逗号隔开显示

Question

需要函数的形式，如fmnum(strnum) strnum=任意数值

Answer 1

<SCRIPT LANGUAGE="JavaScript">
<!--
num="38937031270342073"
num=num.replace(/(\d\d\d)/g,function($0,$1){return $1+","})
alert(num)
//-->
</SCRIPT>

Answer 2

function formatNum(num) //将数字转换成三位逗号分隔的样式
{
  if(!/^(\+|-)?(\d+)(\.\d+)?$/.test(num)){alert("wrong!"); return num;}
  var a = RegExp.$1, b = RegExp.$2, c = RegExp.$3;
  var re = new RegExp().compile("(\\d)(\\d{3})(,|$)");
  while(re.test(b)) b = b.replace(re, "$1,$2$3");
  return a +""+ b +""+ c;
}
alert(formatNum(-12345678.123));
alert(formatNum("12345678.123"));
alert(formatNum("10000000000000000000000000000000000000000"));

Answer 3

function addCommaToNumber(numberStr)
{
var str=numberStr;
var subs=new Array()
var newStr=""
for(var i=str.length,j=0;i>0;i-=3,j++) 
subs[j]=str.substring(i,i-3) 
subs.reverse()
for(var i=0;i<subs.length;i++) 
newStr+=(i==subs.length-1)?subs[i]:subs[i]+","
return newStr
}