class Queue {↵
constructor() { this.items = []; }↵
enqueue(item) { this.items.push(item); }↵
dequeue() { return this.items.shift(); }↵
front() { return this.items[0]; }↵
isEmpty() { return this.items.length === 0; }↵
size() { return this.items.length; }↵
}↵
↵
const queue = new Queue();↵
queue.enqueue("first");↵
queue.enqueue("second");↵
queue.enqueue("third");↵
console.log(queue.front());↵
console.log(queue.dequeue());↵
console.log(queue.dequeue());↵
console.log(queue.size());↵
console.log(queue.front());