数字添加逗号即千分号

<script>
/* 正则 */
function addComma(num) {
return !isNaN(num) && num.replace(/(\d{1,3})(?=(\d{3})+(?:$|\.))/g, "$1,");
}
console.log(addComma("1234567898.36"));

/* 截取字符串 */
function addComma2(str) {
var arr = str.split("."),
strN = arr[0].toString(),
len = strN.length,
index = len % 3,
i,
newStr;
newStr = strN.substr(0, index);
index == 0 && (newStr = strN.substr(0, 3), index = 3);
for (i = index; i < len; i += 3) {
newStr += "," + strN.substr(i, 3);
}
arr[1] && (newStr += "." + arr[1]);
return newStr;
}
console.log(addComma2("1234567898.36"));
</script>