在Javascript中创建定长队列数组

class FixedLengthQueue {
  constructor(length, defaultValue) {
    this.queue = Array(length).fill(defaultValue);
    this.head = 0; // 队列头部指针
    this.tail = 0; // 队列尾部指针
    this.count = 0; // 队列当前元素个数
    this.maxLength = length; // 队列最大长度
  }

  enqueue(element) {
    if (this.count === this.maxLength) {
      // 队列已满，移除头部元素
      this.dequeue();
    }

    this.queue[this.tail] = element;
    this.tail = (this.tail + 1) % this.maxLength; // 环形队列
    this.count++;
  }

  dequeue() {
    if (this.count === 0) {
      return undefined; // 队列为空，返回undefined
    }

    const removedElement = this.queue[this.head];
    this.queue[this.head] = undefined;
    this.head = (this.head + 1) % this.maxLength; // 环形队列
    this.count--;

    return removedElement;
  }

  size() {
    return this.count;
  }

  isEmpty() {
    return this.count === 0;
  }

  isFull() {
    return this.count === this.maxLength;
  }

  clear() {
    this.queue = Array(this.maxLength).fill(undefined);
    this.head = 0;
    this.tail = 0;
    this.count = 0;
  }
}

// 示例用法
const queue = new FixedLengthQueue(5, null);

queue.enqueue(1);
queue.enqueue(2);
queue.enqueue(3);
queue.enqueue(4);
queue.enqueue(5);

console.log(queue.size()); // 输出: 5
console.log(queue.isFull()); // 输出: true

queue.enqueue(6);
console.log(queue.dequeue()); // 输出: 2

queue.clear();
console.log(queue.isEmpty()); // 输出: true