js advance 10. Length Limit

class Stringer {
  constructor(string, length) {
      this.innerString = string;
      this.innerLength = Number(length);
  }
  increase(length) {
      this.innerLength += length;
  }
  decrease(length) {
      this.innerLength = Math.max(this.innerLength - length, 0);
  }
  toString() {
      if (this.innerString.length > this.innerLength) {
          return `${this.innerString.substring(0, this.innerLength)}...`;
      } else if (this.innerString.length <= this.innerLength) {
          return this.innerString;
      } else {
          return `...`;
      }
  }
}