double linked stack

by Taylor Zimmerman

HTML

<p id='output1'></p>
<p id='output2'></p>

JavaScript

var Node = function(_content)
{
	this.next = null;
  this.last = null;
  this.content = _content;
}

var Stack = function()
{
	this.head = null;
  this.top = null;
  this.push = function(_content)
  {
  	if (this.head == null)
    {
    	this.head = new Node(_content);
      this.top = this.head;
      return this;
    }
    var addedNode = new Node(_content);
    addedNode.last = this.top
    this.top.next = addedNode;
    this.top = addedNode;
    return this;
  }
  
  this.pop = function()
  {
  	if (this.head == null)
    {
    	alert("The stack is empty");
      return null;
    }
    var a = this.top;
    this.top = this.top.last;
    this.top.next = null;
    
    return a;
  }
  this.toString = function()
  {
  	var str = "";
    var node = this.head;
    
    while (node != null)
    {
    	str += node.content + ":";
      node = node.next;
    }
    return str;
  }
}


// create a linked list and add nodes
var stack = new Stack();
stack.push('A');
stack.push('B');
stack.push('C');
stack.push('D');
stack.push('E');

document.getElementById('output1').innerHTML = 'Push some nodes ' + stack.toString();
stack.pop();
stack.pop();
  
document.getElementById('output2').innerHTML = "Pop some Objects: " + stack.toString();