__defineGetter__ && __defineSetter__

看别人源码碰到的，做个备忘。

//针对对象增加get\set方法，返回绑定函数的返回值
Date.prototype.__defineGetter__('getYear', function() {return this.getFullYear();});
Date.prototype.__defineSetter__('setYear', function(year) {this.setFullYear(year)});
Date.prototype.__defineGetter__('sayHello', function() {return "Hello"}); 

var now = new Date;
console.log(now.getYear); //2015
now.setYear  = 2011;
console.log(now.getYear); //

console.log(now.sayHello);