Demo: https://repl.it/@NegarJF/Stack

Stack.js

class Stack{

  constructor(){
    this.top = null;
    this.size = 0;
  }

  get isEmpty(){
    return this.top === null;
  }

  get peek(){
    return this.top.data; 
  }

  push(data){
    const node = new Node(data);
    node.next = this.top;
    this.top = node;
    this.size++;
  }

  pop(){
    const data = this.top.data;
    this.top = this.top.next;
    this.size--;

    return data;
  }
}


class Node{
  constructor(data){
    this.data = data;
    this.next = null;
  }
}

module.exports = Stack;