JS inheritance

js-inheritance.js

if (!Function.prototype.bind) {
	Function.prototype.bind = function (context) {
		if (typeof this !== 'function') throw new TypeError('Function.prototype.bind - what is trying to be bound is not callable');
		var args = Array.prototype.slice.call(arguments, 1),
			fToBind = this,
			fn = function () {},
			fBound = function () {
				return fToBind.apply(this instanceof fn && context ? this : context,
					args.concat(Array.prototype.slice.call(arguments)));
			};
		fn.prototype = this.prototype;
		fBound.prototype = new fn();
		return fBound;
	};
}

Function.prototype.extend = function (parent) {
	this.prototype = new parent();
	this.prototype._super = new parent();
	var self = this;
	for (var m in this.prototype._super) {
		if (typeof this.prototype._super[m] === 'function')
			this.prototype._super[m] = this.prototype._super[m].bind(this);
	}
	return this;
};


function Animal(v) { this.type = 'animal'; }
Animal.prototype.validate = function () { console.log('is animal: ', this.type === 'animal'); };


function Dog(v) { this.type = 'dog'; }
Dog.extend(Animal);
Dog.prototype.validate = function () {
	console.log('is dog: ', this.type === 'dog');
	this._super.validate();
};
Dog.prototype.bark = function () { console.log('hau hau'); };


var a = new Animal(true);
a.validate();

var d = new Dog(10);
d.validate();

// console.log(d)