I am trying to understand JavaScripts Prototypal nature and I am trying to create object inheritance without using class like constructor functions.
How can I attach the prototype chain from Animals and then each to Cat and Dog if they are all three object literals?
Also, is there a way to do an Object.create and add more properties in literal form (like myCat).
I've added the code below & to paste bin http://jsbin.com/eqigox/edit#javascript
var Animal = {
name : null,
hairColor : null,
legs : 4,
getName : function() {
return this.name;
},
getColor : function() {
console.log("The hair color is " + this.hairColor);
}
};
/* Somehow Dog extends Animal */
var Dog = {
bark : function() {
console.log("Woof! My name is ");
}
};
/* Somehow Cat Extends Animal */
var Cat = {
getName : function() {
return this.name;
},
meow : function() {
console.log("Meow! My name is " + this.name);
}
};
/* myDog extends Dog */
var myDog = Object.create(Dog);
/* Adding in with dot notation */
myDog.name = "Remi";
myDog.hairColor = "Brown";
myDog.fetch = function() {
console.log("He runs and brings back it back");
};
/* This would be nice to add properties in litteral form */
var myCat = Object.create(Cat, {
name : "Fluffy",
hairColor : "white",
legs : 3, //bad accident!
chaseBall : function(){
console.log("It chases a ball");
}
});
myDog.getColor();
You can use Object.create
to use your defined objects as prototypes. For instance:
var Dog = Object.create(Animal, {
bark : {
value: function() {
console.log("Woof! My name is " + this.name);
}
}
});
Now you can create a new Dog object:
var myDog = Object.create(Dog);
myDog.bark(); // 'Woof! My name is null'
myDog.getColor(); // 'The hair color is null'
Example: http://jsfiddle.net/5Q3W7/1/
Alternatively, if you're working in the absence of Object.create
, you can use constructors:
function Animal() {
this.name = null;
this.hairColor = null;
this.legs = 4;
};
Animal.prototype = {
getName : function() {
return this.name;
},
getColor : function() {
console.log("The hair color is " + this.hairColor);
}
}
function Dog() {
}
Dog.prototype = new Animal;
Dog.prototype.bark = function() {
console.log("Woof! My name is " + this.name);
};
Example: http://jsfiddle.net/5Q3W7/2/
For more information about Object.create: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/create/
For more information about Constructors and prototypes chains: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/constructor
https://developer.mozilla.org/en/JavaScript/Guide/Inheritance_and_the_prototype_chain