友元

友元:指一个对象向另一个对象开放其特定私有属性和方法的访问权限

 

一个小例子:

 

function dw(s){ document.writeln(s+"<br />");} function ClassA(){ var a = 100; var b = 200; var that = this; this.declareFriend = function(friend){ friend.getPrivateProperty = function(privateName){ return eval(privateName); } } } var objA = new ClassA(); var objB = {}; objA.declareFriend( objB ); dw( objB.getPrivateProperty("a") ); dw( objB.getPrivateProperty("b") );