StacksAndQueues.js

class Stack {
  constructor () {
    this.storage = {}
    this.size = 0
  }


  push(element) {
    this.size++
    this.storage[this.size] = element
  }

  pop() {
    let removed = this.storage[this.size]
    delete this.storage[this.size]
    this.size--
    return removed
  }

  peek() {
    return this.storage[this.size]
  }
}

const stack = new Stack()

stack.push('dog')
stack.push('cat')
stack.push('bear')

stack.pop()

stack.peek()

Source: https://www.youtube.com/watch?v=1AJ4ldcH2t4