给对象动态增加职责的方式称为装饰者模式。
Function.prototype.before = function(beforefn){
var _self = this;
return function(){
beforefn.apply(this,arguments);
return _self.apply(this,arguments);
}
}
Function.prototype.after = function(afterfn){
var _self = this;
return function(){
var ret = _self.apply(this,arguments);
afterfn.apply(this,arguments);
return ret;
}
}