JS添分隔符

JS加分隔符
    //每四位加分隔符
    function cc(s){
        if(null == s || "" == s) return "";
        if(/[^0-9\.]/.test(s)) return "invalid value";
        s=s.replace(/^(\d*)$/,"$1.");
        s=(s+"00").replace(/(\d*\.\d\d)\d*/,"$1");
        s=s.replace(".",",");
        var re=/(\d)(\d{3},)/;
        while(re.test(s))
                s=s.replace(re,"$1,$2");
        s=s.replace(/,(\d\d)$/,".$1");
        return s.replace(/^\./,"0.");
    }