Saturday Oct 14, 2006
This functionality is not built into JavaScript, so custom code needs to be used. The following is one way of adding commas to a number, and returning a string.

function eInterNextaddCommas(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;
}