js code to add commas to numbers and format numbers_javascript skills

Copy code The code is as follows:

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;
}

//Number formatting can become
var num = 123456.4231;
num = num.toFixed(2 );
num =addCommas(num);
// num = 123456.42