zoo.js

//------------------------------------------------------------------------------------------------------------------
// YOUR CODE: Create your Zoo "object literal" and Animal "constructor" and "prototypes" here.
//------------------------------------------------------------------------------------------------------------------

function Animal(name, legs){
  this.name = name
  this.legs = legs
}

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

var Zoo = {
  init: function(animals){
    this.animals = animals
  },

  bipeds: function(){
    return this.animals.filter(function(animal){
      return animal.legs === 2;
      })
  },

  quadrupeds: function(){
    return this.animals.filter(function(animal){
      return animal.legs === 4;
      })
  }
}



//------------------------------------------------------------------------------------------------------------------
//  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 bipeds"
);
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"
);