[css] Formatting numbers (decimal places, thousands separators, etc) with CSS

Well, for any numbers in Javascript I use next one:

var a = "1222333444555666777888999";
a = a.replace(new RegExp("^(\\d{" + (a.length%3?a.length%3:0) + "})(\\d{3})", "g"), "$1 $2").replace(/(\d{3})+?/gi, "$1 ").trim();

and if you need to use any other separator as comma for example:

var sep = ",";
a = a.replace(/\s/g, sep);

or as a function:

function numberFormat(_number, _sep) {
    _number = typeof _number != "undefined" && _number > 0 ? _number : "";
    _number = _number.replace(new RegExp("^(\\d{" + (_number.length%3? _number.length%3:0) + "})(\\d{3})", "g"), "$1 $2").replace(/(\d{3})+?/gi, "$1 ").trim();
    if(typeof _sep != "undefined" && _sep != " ") {
        _number = _number.replace(/\s/g, _sep);
    }
    return _number;
}