class Stack { constructor() { this.array = []; } peek() { return this.array[this.array.length - 1]; } push(value) { this.array.push(value); } pop() { this.array.pop(); return this; } } const stack = new Stack(); stack.push(10); stack.push(12); stack.push(11); stack.push(14); stack.pop(); stack.pop(); stack.pop(); // stack.pop(); stack.pop(); // stack.pop(); // stack.pop(); console.log(stack.pop());