stack

function createStack() {
  const array = [];
  return {
    push(item) {
      array.push(item);
    },
    pop() {
      return array.pop();
    },
    get length() {
      return array.length;
    },
    peek() {
      return array[array.length -1];
    }
  }
}

const stack = createStack();
stack.push(1);
stack.push(20);
stack.push('hello');

console.log(stack.length)
console.log(stack.peek());
stack.pop();
console.log(stack.peek());