Javascript Data Structure Tutorial - Javascript Stack

 
function Stack() { /*from  w  ww .  ja v a  2 s  .  c o  m*/
    this.dataStore = []; 
    this.top = 0; 
    this.push = push; 
    this.pop = pop; 
    this.peek = peek; 
    this.length = length;
    this.clear = clear;
} 
//push() can push a new element 
//onto a stack. Here is the code: 
function push(element) { 
    this.dataStore[this.top++] = element; 
} 
//The pop() function does the reverse of the push() function.
//It returns the element in the top position of the stack and then decrements the top variable: 
function pop() { 
    return this.dataStore[--this.top]; 
} 
//The peek() function returns the top element of the stack by accessing the element at 
//the top-1 position of the array: 
function peek() { 
    return this.dataStore[this.top-1]; 
} 
//The length() function returns this value by returning the value of top: 
function length() { 
    return this.top; 
} 
//we can clear a stack by simply setting the top variable back to 0: 
function clear() { 
    this.top = 0; 
} 

var s= new Stack(); 
s.push("D"); 
s.push("R"); 
s.push("B"); 
console.log("length: " + s.length()); 
console.log(s.peek()); 

var popped = s.pop(); 
console.log("The popped element is: " + popped); 
console.log(s.peek()); 
s.push("C"); 
console.log(s.peek()); 
s.clear(); 
console.log("length: " + s.length()); 
console.log(s.peek()); 
s.push("B"); 
console.log(s.peek());

var Stack = function(){
  this.storage = {};//from  ww w  .  ja va2 s  .co  m
  this.stackSize = 0;
};


Stack.prototype.push = function(value){
  this.storage[this.stackSize++] = value;
};

Stack.prototype.pop = function(){
  if (this.stackSize) {
    var temp = this.storage[this.stackSize - 1];
    return (delete this.storage[this.stackSize--]) && temp;
  }
};

Stack.prototype.size = function(){
  return this.stackSize;
};