Method _collapseTo

specs/arrays/arraylist.solution.test.js:43–49

(index)

    return ans;
  }
  _collapseTo(index) {
    for (let i = index; i < this.length; i++) {
      this.data[i] = this.data[i + 1];
    }
    delete this.data[this.length - 1];
    this.length--;
  }
  serialize() {
    return this.data;
  }