stack_with_string_as_storage.js

var Stack = function(){
  this.storage = "";
  this.frameSize = 20;
  this.emptySpaceChar = '$';
};

Stack.prototype.paddingRight = function(val) {
  for(var i = val.length; i <= this.frameSize; i++) {
    val += this.emptySpaceChar;
  }

  return val;
}

Stack.prototype.validateValue = function(val) {
  if (typeof val != "string") {
    throw new Error("Item can only be a string");
  }
  if (val.indexOf('$') != -1) {
    throw new Error("Item cannot contain the empty space character: " + this.emptySpaceChar);
  }
  if (val.length > this.frameSize) {
    throw new Error("Item cannot be longer than " + this.frameSize + " characters");
  }
}

Stack.prototype.push = function(val){
  this.validateValue(val);

  val = this.paddingRight(val);
  this.storage += val;
};

Stack.prototype.pop = function(){
  var newEnd = this.storage.length - this.frameSize - 1;
  var top = this.storage.substr(newEnd, this.storage.length);
  this.storage = this.storage.substr(0, newEnd);

  top = top.substr(0, top.indexOf(this.emptySpaceChar));
  return top;
};

Stack.prototype.size = function(){
  return this.storage.length / this.frameSize;
};

var myWeeklyMenu = new Stack();

myWeeklyMenu.push("RedBeans");
myWeeklyMenu.push("Pasta");
myWeeklyMenu.push("Rice and beans");
myWeeklyMenu.push("Salad");

while(myWeeklyMenu.size()) {
  console.log(myWeeklyMenu.pop());
}