gistfile1.txt

//Creates a node containing the data and a reference to the next item
function createNode(data = null, next = null) {
  return {
    data,
    next
  };
}

class Stack {
  constructor() {
    this.top = null;
  }

  push(data) {
    //if the top of the stack is empty, then the data will be the
    //top of the stack
    if (this.top === null) {
      this.top = createNode(data);
      return;
    }

    //if the top already has something then create a new node
    //add data to the new node
    // have the pointer point to the top
    const node = createNode(data, this.top);
    this.top = node;
  }

  pop() {
    //in order to remove the top of the stack, you have to point
    //the pointer to the next item and that next item becomes the
    //top of the stack
    const node = this.top;
    this.top = node.next;
    return node.data;
  }
}

let s = new Stack();

s.push(1);
s.push(2);
s.push("Tauhida");
//console.log("Top of stack:", peek(s));

s.pop();
s.push("joe");
//console.log("Top of stack:", peek(s));

display();

function peek() {
  //if the top of the stack does not have anything
  //then the stack is empty
  //otherwise return what's on the top
  if (s.top === null) {
    return null;
  }
  return s.top.data;
}

function display() {
  // displays the entire contents of the stack
  let node = s.top;
  while (node !== null) {
    //console.log(node.data);
    node = node.next;
  }
}

let balancedStack = new Stack();