JS Class继承类：模拟面向对象继承

使用方式：

 

/**
 * Person = Class.extend({
 * 		init: function(){}
 * });
 * 
 * Student = Person.extend({
 * 		init: function(){}
 * });
 */

 源代码：

/**废弃该方式，采用base.js         (function() {
	var k = false, 
	t = /xyz/.test(function() {}) ? /\b_super\b/ : /.*/;
	this.Class = function() {
	};
	Class.extend = function(q) {
		function w() {
			!k && this.init && this.init.apply(this, arguments)
		}
		var K = this.prototype;
		k = true;
		var O = new this;
		k = false;
		for ( var C in q)
			O[C] = typeof q[C] == "function" 
				&& typeof K[C] == "function"
				&& t.test(q[C]) 
				? function(fa, qa) {
					return function() {
						var p = this._super;
						this._super = K[fa];
						var u = qa.apply(this, arguments);
						this._super = p;
						return u
					}
				}(C, q[C]) : q[C];
		w.prototype = O;
		w.constructor = w;
		w.extend = arguments.callee;
		return w;
	};
})();*/

Base.js

/*
	Base.js, version 1.1a
	Copyright 2006-2009, Dean Edwards
	License: http://www.opensource.org/licenses/mit-license.php
*/

var Base = function() {
	// dummy
};

Base.extend = function(_instance, _static) { // subclass
	var extend = Base.prototype.extend;
	
	// build the prototype
	Base._prototyping = true;
	var proto = new this;
	extend.call(proto, _instance);
	proto.base = function() {
		// call this method from any other method to invoke that method's ancestor
	};
	delete Base._prototyping;
	
	// create the wrapper for the constructor function
	//var constructor = proto.constructor.valueOf(); //-dean
	var constructor = proto.constructor;
	var klass = proto.constructor = function() {
		if (!Base._prototyping) {
			if (this._constructing || this.constructor == klass) { // instantiation
				this._constructing = true;
				constructor.apply(this, arguments);
				delete this._constructing;
			} else if (arguments[0] != null) { // casting
				return (arguments[0].extend || extend).call(arguments[0], proto);
			}
		}
	};
	
	// build the class interface
	klass.ancestor = this;
	klass.extend = this.extend;
	klass.forEach = this.forEach;
	klass.implement = this.implement;
	klass.prototype = proto;
	klass.toString = this.toString;
	klass.valueOf = function(type) {
		//return (type == "object") ? klass : constructor; //-dean
		return (type == "object") ? klass : constructor.valueOf();
	};
	extend.call(klass, _static);
	// class initialisation
	if (typeof klass.init == "function") klass.init();
	return klass;
};

Base.prototype = {	
	extend: function(source, value) {
		if (arguments.length > 1) { // extending with a name/value pair
			var ancestor = this[source];
			// overriding a method?
			// the valueOf() comparison is to avoid circular references
			if (ancestor && (typeof value == "function") && 
				(!ancestor.valueOf || ancestor.valueOf() != value.valueOf()) &&
				/\bbase\b/.test(value)) {
				// get the underlying method
				var method = value.valueOf();
				// override
				value = function() {
					var previous = this.base || Base.prototype.base;
					this.base = ancestor;
					var returnValue = method.apply(this, arguments);
					this.base = previous;
					return returnValue;
				};
				// point to the underlying method
				value.valueOf = function(type) {
					return (type == "object") ? value : method;
				};
				value.toString = Base.toString;
			}
			this[source] = value;
		} else if (source) { // extending with an object literal
			var extend = Base.prototype.extend;
			// if this object has a customised extend method then use it
			if (!Base._prototyping && typeof this != "function") {
				extend = this.extend || extend;
			}
			var proto = {toSource: null};
			// do the "toString" and other methods manually
			var hidden = ["constructor", "toString", "valueOf"];
			// if we are prototyping then include the constructor
			var i = Base._prototyping ? 0 : 1;
			while (key = hidden[i++]) {
				if (source[key] != proto[key]) {
					extend.call(this, key, source[key]);

				}
			}
			// copy each of the source object's properties to this object
			for (var key in source) {
				if (!proto[key]) extend.call(this, key, source[key]);
			}
		}
		return this;
	}
};

// initialise
Base = Base.extend({
	constructor: function() {
		this.extend(arguments[0]);
	}
}, {
	ancestor: Object,
	version: "1.1",
	
	forEach: function(object, block, context) {
		for (var key in object) {
			if (this.prototype[key] === undefined) {
				block.call(context, object[key], key, object);
			}
		}
	},
		
	implement: function() {
		for (var i = 0; i < arguments.length; i++) {
			if (typeof arguments[i] == "function") {
				// if it's a function, call it
				arguments[i](this.prototype);
			} else {
				// add the interface using the extend method
				this.prototype.extend(arguments[i]);
			}
		}
		return this;
	},
	
	toString: function() {
		return String(this.valueOf());
	}
});

Class = Base;