JavaScript 实现数字千分位分隔符的简单方法

<!DOCTYPE html> 
<html> 
<head> 
<meta charset="utf-8"> 
<title>给字符加千分号</title> 
<script type="text/javascript"> 
var str = '2359844564654'; 
function test3(str) { 
var iNum = str.length%3; //余数 
var prev = ''; 
var arr = []; 
var iNow = 0; 
var tmp = ''; 
if(iNum !=0) { 
prev = str.substring(0,iNum); //将余数截取出来 
arr.push(prev); 
} 
str = str.substring(iNum); 
for(var i=0;i<str.length;i++) { 
iNow++; 
tmp +=str[i]; 
if(iNow ==3 && tmp) { 
arr.push(tmp); 
tmp = ''; 
iNow = 0; 
} 
} 
return arr.join(','); 
} 
alert(test3(str)); 
</script> 
</head> 
<body> 
<p></p> 
</body> 
</html>