Data Structures - Stack in JS without using Array - Full Demo: https://jsfiddle.net/dpnminh/g1xy22cz/

Stack.js

function Stack(){
  var stack = {};
  var stackSize = 0;
  
  return {
    push: function(item){
      stack[stackSize] = item;
      stackSize++;
    },
    pop: function(){
    	if (this.isEmpty()){ return undefined;}
      
      stackSize--;
      
    	var item = stack[stackSize];
      delete stack[stackSize];
      
      return item;      
    },
    peek: function(){
    	if (this.isEmpty()){
      	return undefined;
      }
      
      return stack[stackSize - 1];
    },
    stackEmpty: function(){      
      while (!this.isEmpty()){
        this.pop();
      }
    },
    isEmpty: function(){
    	return stackSize === 0;
    },
    size: function(){
    	return stackSize;
    },
    print: function(){
    	var result = [];
      
    	for (var key in stack){
        result.unshift(stack[key]);
      }
      
      return result;
    }
  }	
}