JS Data Structures: Stacks, see more at: https://medium.com/p/7dcea711c091

DATA_STRUCTURES_stackUsingJSNativeMethods.js

function Stack() {
  let items = []

  class PublicStack {
    peek() {
      if (this.isEmpty()) throw new Error('Stack is empty')
      const lastItemIndex = items.length - 1

      return items[lastItemIndex]
    }

    pop() {
      if (this.isEmpty()) throw new Error('Stack is empty')

      items.pop()
    }

    push(data) {
      items.push(data)
    }

    isEmpty() {
      return this.size() === 0
    }

    size() {
      return items.length
    }
  }

  return new PublicStack()
}

const myStack = new Stack()