zoo.js

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

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


// Zoo Object Literal
var Zoo = {
  init: function(animal_array) {
    this.animal_array = animal_array;
  }
}


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


// Extend Zoo Prototype
Zoo.bipeds = function() {
  var biped_array = []
  for (i=0; i< this.animal_array.length; i++) {
    if (this.animal_array[i].legs === 2){
      biped_array.push(this.animal_array[i])
    }
  }
  return biped_array;
}

Zoo.quadrupeds = function() {
  var quadruped_array = [];
  for (i=0; i< this.animal_array.length; i++) {
    if (this.animal_array[i].legs === 4){
      quadruped_array.push(this.animal_array[i])
    }
  }
  return quadruped_array;
}


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