animals.js run this on repl.it

animals.js

Animal = function(name,sound) {
    if(name) {
        this.name = name;
  }
    if(sound) {
        this.sound = sound;
    }
}

Animal.prototype = {
	introduce: function() {
		console.log("The " + this.name + " goes " + this.sound);
	},

	isAnimal: function() {
		return !!this.animal;
	},
    
	isMammal: function() {
		return !!this.mammal;
	},
    
    isReptile: function() {
        return !!this.reptile;
    },
    
    isBird: function() {
        return !!this.bird;
    }
}
Animal.prototype.animal = true;

Mammal = function(name,sound) {
	Animal.apply(this, [name,sound]);
}
Mammal.prototype = new Animal;
Mammal.prototype.mammal = true;

Reptile = function(name, sound) {
	Animal.apply(this, [name,sound]);
}
Reptile.prototype = new Animal;
Reptile.prototype.reptile = true;

Bird = function(name, sound) {
	Animal.apply(this, [name,sound]);
}
Bird.prototype = new Animal;
Bird.prototype.bird = true;

Fish = function(name, sound) {
	Animal.apply(this, [name,sound]);
}
Fish.prototype = new Animal;
Fish.prototype.fish = true;

fox = new Mammal("fox", "ancient mystery");

console.log(fox.isBird());
console.log(fox.isMammal());

elephant = new Mammal("elephant", "ewaaaaaa!!");
cow = new Mammal("cow", "moo");
goldfish = new Fish("goldfish", "blub");
parakeet = new Bird("parakeet", "tweet");
elephant.introduce();
cow.introduce();
goldfish.introduce();
parakeet.introduce();
fox.introduce();