js框架中类继承的比较
2010-07-13 09:24:16.0
首先我们来看下jQuery之父john resig的实现方法:
jq之父写的类继承方式的特点是:
- 有私有变量
- 可以写在一个构造函数中
- 可以多级继承，可以有多个父类（需要某种特定格式）
- 继承基于prototype，且不会执行父类的构造函数
- 保持了父类的函数链，可以在子类中用this._super简单调用
- instanceof 对子类、父类都生效
这是目前为止我看到的最好的方法。除了定义了一个全局变量Class外
// Inspired by base2 and Prototype
(function(){
var initializing = false, fnTest = /xyz/.test(function(){xyz;}) ? /\b_super\b/ : /.*/;
// The base Class implementation (does nothing)
this.Class = function(){};
// Create a new Class that inherits from this class
Class.extend = function(prop) {
var _super = this.prototype;
// Instantiate a base class (but only create the instance,
// don't run the init constructor)
initializing = true;
var prototype = new this();
initializing = false;
// Copy the properties over onto the new prototype
for (var name in prop) {
// Check if we're overwriting an existing function
prototype[name] = typeof prop[name] == "function" &&
typeof _super[name] == "function" && fnTest.test(prop[name]) ?
(function(name, fn){
return function() {
var tmp = this._super;
// Add a new ._super() method that is the same method
// but on the super-class
this._super = _super[name];
// The method only need to be bound temporarily, so we
// remove it when we're done executing
var ret = fn.apply(this, arguments);
this._super = tmp;
return ret;
};
})(name, prop[name]) :
prop[name];
}
// The dummy class constructor
function Class() {
// All construction is actually done in the init method
if ( !initializing && this.init )
this.init.apply(this, arguments);
}
// Populate our constructed prototype object
Class.prototype = prototype;
// Enforce the constructor to be what we expect
Class.constructor = Class;
// And make this class extendable
Class.extend = arguments.callee;
return Class;
};
})();