javascript AOP 实现ajax回调函数使用比较方便

function actsAsDecorator(object) { 
object.setupDecoratorFor = function(method) { 
if (! ('original_' + method in object) ) { 
object['original_' + method] = object[method]; 
object['before_' + method] = [ ]; 
object['after_' + method] = [ ]; 
object[method] = function() { 
var i; 
var b = this['before_' + method]; 
var a = this['after_' + method]; 
var rv; 
for (i = 0; i < b.length; i++) { 
b[i].call(this, arguments); 
} 
rv = this['original_' + method].apply(this, arguments); 
for (i = 0; i < a.length; i++) { 
a[i].call(this, arguments); 
} 
return rv; 
} 
} 
}; 
object.before = function(method, f) { 
object.setupDecoratorFor(method); 
object['before_' + method].unshift(f); 
}; 
object.after = function(method, f) { 
object.setupDecoratorFor(method); 
object['after_' + method].push(f); 
}; 
} 
/** 
Invoking 
*/ 
function Test(){ 
this.say1 = function(s){ 
alert(s); 
} 
this.say2 = function(s){ 
alert(s); 
} 
} 
var t = new Test(); 
actsAsDecorator(t); 
t.before("say1",beforeHander); 
t.after("say2",afterHander); 
test();