class Queue { constructor() { this.array = []; } peek() { return this.array[this.array.length - 1]; } push(value) { this.array.unshift(value); } pop() { return this.array.pop(); } empty() { return !this.array.length; } } const queue = new Queue(); queue.push(1); queue.push(2); console.log(queue); console.log(queue.peek()); console.log(queue.pop()); console.log(queue.empty());