js为数字添加逗号并格式化数字的代码

function addCommas(nStr)
{
nStr += '';
x = nStr.split('.');
x1 = x[0];
x2 = x.length > 1 ? '.' + x[1] : '';
var rgx = /(\d+)(\d{3})/;
while (rgx.test(x1)) {
x1 = x1.replace(rgx, '$1' + ',' + '$2');
}
return x1 + x2;
}

//数字格式化就可以变成
var num = 123456.4231;
num = num.toFixed(2);
num =addCommas(num);
// num = 123456.42