Prototypical inheritence in JavaScript is actually kind of cool, but in addition to deviating from the inheritance most people are used to, it's annoyingly hard to use (Object.create wasn't even added until ES5, and even that is a little unfriendly). Proto.js embraces JavaScripts prototypical inheritance and makes it easy to create new objects that extend a prototype using a concise syntax enabled by JavaScript's object literals.

create is how you create new objects that extend other objects:

// indicate that an object is a prototype with StudlyCaps
var Person = Proto.create({
	greet: function() {
		return "Hello " + this.name + "!".
	}
});

var joe = Person.create({name: "Joe"});
joe.greet() --> "Hello Joe!"

Proto.js objects are re-openable, and extend allows you to attach methods and objects to existing objects just like during create:

Person.extend({
	greetLoudly: function() {
		return this.greet().toUpperCase();
	}
});

joe.greetLoudly() --> "HELLO JOE!";

Proto.js object make it possible to override existing methods, but still call them:

var LoudPerson = Person.create({
	greet: function() {
		// Lets us search the prototype chain starting above the object we pass in.
		var message = this._super(LoudPerson).greet();
		return message.toUpperCase();
	}
});

var jill = LoudPerson.create({name: "Jill"});
jill.greet() --> "HELLO JILL!";

Methods on Proto.js objects are bound by default (you can still get at the unbound methods in __methods__ if you need to):

var f = joe.greet;
f() --> "Hello Joe!"

var g = joe.__methods__.greet;
g() --> "Hello undefined!"

Licensed under the Apache Public License v2.0