format

String.prototype.format = function(){
  let ret = this + ""
  let matches = this.matchAll(/{([^}]*)}/g);
    let i = 0;
  for (let match of matches) {
        let tag = match[1];
    let index = Number(tag)
        if (!tag || isNaN(index)) {index = i;++i}
        ret = ret.replace(/{[^}]*}/, arguments[index]);
    }
    return ret;
}