数据结构-js实现-栈

class Stack {
  constructor() {
    this.items = [];
  }

  push(item) {
    this.items.push(item);
  }

  pop() {
    return this.items.pop();
  }

  // 返回顶部元素，但是不修改
  peek() {
    return this.items.at(-1);
  }

  isEmpty() {
    return this.items.length === 0;
  }
  clear() {
    this.items = [];
  }
  size() {
    return this.items.length;
  }

  toString() {
    if (this.isEmpty()) {
      return "";
    }
    let objString = `${this.items[0]}`;
    for (let i = 1; i < this.count; i++) {
      objString = `${objString},${this.items[i]}`;
    }
    return objString;
  }
}