test.html

<script src="zoo.js" type="text/javascript"></script>

<!-- I used this html file to test how my JS code was loading in the console. -->
<!-- s -->

zoo.js

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

var Zoo = {
  // init: function(animals) {
  // this.bipeds = [];
  // this.quadrupeds = [];
  // },
  bipeds: function() {
    return bipeds;
  },
  quadrupeds: function() {
    return quadrupeds;
  }

};

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

  // this.identify = function() {
  //   return "I am a "+this.name+" with "+this.legs+" legs.";
  // }
  // This is bad, because comparisons between two animals will return false for this function, even if they are technically the same
  // A prototype's methods should be defined using the 'prototype' syntax
}

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

Animal.prototype.name = function() {
  return name;
}

// Can I also do this?:

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


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