[JS] 숫자에 콤마 붙이기

function addComma(x) {
    var idx = 0;
    while(true){
        idx = x.indexOf(",");
        x = x.replace(",","");
        if(idx<0){break;}
    }
    //console.log(x);
    return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
}