spawnjs v1.0.2

spawnjs

A utility library for prototypal inheritance

Object.create is useful for creating new objects using old objects as prototypes. Well, spawn goes one step further. Here's an example of how spawn can be useful to you:

Say I wanted object child to inherit from object parent, and I wanted child to have some properties of its own. Here's how I would do it using Object.create().

var parent = {
	baseProperty: true
};

var child = Object.create(parent);

child.childProperty1 = 3;
child.childProperty2 = "a string";

Let's see if we can make that a little more concise, shall we?

var parent = spawn({
	baseProperty: true
});

var child = parent.spawn({
	childProperty1: 3,
	childProperty2: "a string"
});

That's it! spawn simply creates an object based on a prototype, and in turn makes that object spawnable. The word "spawn" also implies creating an offspring that is based on a prototype, but with a mind of its own, as opposed to "extend", which implies that you are adding properties to the original object without creating a new one.

spawn also includes a cleaner way of thinking about inheritance of so-called JavaScript "classes," (based on John Resig's inheritance implementation) but calls them, more appropriately, "constructors," and uses "spawn," rather than "extend," to, well, spawn. extend makes sense when you're in a classical language where classes extend other classes. But the behavior is fundamentally different in JavaScript, so it needs a different name.

var ParentConstructor = spawn.Constructor.spawn({
	newMethod: function() {
		return "I'm from a method!";
	}
});

var ChildConstructor = ParentConstructor.spawn({
	newMethod: function() {
		return this._super() + " And the method is on the child constructor!";
	}
});

SpawnJS's source code is only 90 lines long, and the core logic is only 65 lines long. Try it out, and give the source code a read, too!

Installation

SpawnJS is available via NPM and Bower. Check it out:

npm install spawnjs

bower install spawnjs

Usage

SpawnJS uses universal module loading, so you can load it via RequireJS, CommonJS/Browserify, or just plain old browser globals. Check it out:

RequireJS:

You'll need to map a path to "spawnjs" from "bower_components/spawnjs/src":

require.config({
	paths: {
		"spawnjs": "bower_components/spawnjs/src"
	}
});

require(["spawnjs/index", "spawnjs/Constructor"], function(spawn, Constructor) {
	console.log("The spawn function is ", spawn);
	console.log("The Constructor spawner is ", Constructor);
});

CommonJS:

var spawn = require("spawnjs"),
	Constructor = require("spawnjs/Constructor");

spawn({ an: "object" });

var MakeConstructor = Constructor.spawn({ add: "methods" });

Globals:

<script src="bower_components/spawnjs/dist/spawn.min.js"></script>

var spawn = window.spawn,
	Constructor = window.spawn.Constructor;

spawn({ an: "object" });
var MakeConstructor = Constructor.spawn({ add: "methods" });