zoo.js

//------------------------------------------------------------------------------------------------------------------
// YOUR CODE: Create your Zoo "object literal" and Animal "constructor" and "prototypes" here.
//------------------------------------------------------------------------------------------------------------------
var Zoo = {
  animals : [],
  init : function(animal_array){
    animals = animal_array;
  },
  animals : function(){
    return animals
  },
  bipeds : function(){
    var bipedAnimals = [];
    for (var i = 0; i < animals.length; i++) {
      if (animals[i].legs() === 2){
        bipedAnimals.push(animals[i]);
      }
    }
    return bipedAnimals;
  },
  quadrupeds : function(){
    var quadAnimals = [];
    for (var i = 0; i < animals.length; i++) {
      if (animals[i].legs() === 4){
        quadAnimals.push(animals[i]);
      }
    }
    return quadAnimals;
  }
};

function Animal(type, legs) {
  this.myName = type;
  this.myLegs = legs;
  this.name = function(){
    return this.myName;
  };
  this.legs = function(){
    return this.myLegs;
  };
};

Animal.prototype.identify = function() {
  return "I am a " + this.name() + " with " + this.legs() + " legs."
};



//------------------------------------------------------------------------------------------------------------------
// DRIVER CODE: Do **NOT** change anything below this point. Your task is to implement code above to make this work.
//------------------------------------------------------------------------------------------------------------------

function assert(test, message) {  
  if (!test) {
    throw "ERROR: " + message;
  }
  return true;
};

var animals = [
  new Animal("Human", 2),
  new Animal("Monkey", 2),
  new Animal("Kangaroo", 2),
  new Animal("Horse", 4),
  new Animal("Cow", 4),
  new Animal("Centipede", 100)
];

Zoo.init(animals);

assert(
  Zoo.bipeds().length === 3, "the Zoo should have 3 bipeds"
);
assert(
  Zoo.quadrupeds().length === 2, "the Zoo should have 2 quadrupeds"
);
assert(
  animals[0].identify() === "I am a Human with 2 legs.", "humans have 2 legs"
);
assert(
  animals[2].name() === "Kangaroo", "expected 'Kangaroo'"
);
assert(
  animals[0].identify === animals[5].identify, "only one implementation of the identify() function should exist"
);