javaScript的類型函數(shù)（如Number/String/Boolean/Array/Date/Obejct等）都是繼承于 Function.prototype，所以給Function.prototype增加方法，同時(shí)也會(huì)影響到由它衍生的下層類型函數(shù)。如：

復(fù)制代碼代碼如下:

 
Function.prototype.addMethod=function(methodName,func){ 
if(!this[methodName]){ 
this[methodName]=func;//給類型增加方法，類似于類型的靜態(tài)方法。func方法是賦于了類型而非實(shí)例。 
} 
return this;//this 將綁定到方法的調(diào)用對(duì)象(類型函數(shù)),返回this可以進(jìn)行鏈?zhǔn)秸{(diào)用 
} 
Array.addMethod('testFun',function(){alert(this)}); 
//Array.testFun(); //function Array() {[native code]} 
Object.addMethod('testFun',function(){alert(this)}); 
//Object.testFun(); //function Object() {[native code]} 
Boolean.addMethod('testFun',function(){alert(this)}); 
//Boolean.testFun(); //function Boolean() {[native code]} 
function CustomObject(name,value){ 
this.name=name || 'CustomObject'; 
this.value=value || 0; 
this.toString=function(){return '[name:'+this.name+',value:'+this.value+']'} 
} 
CustomObject.addMethod('testFun',function(){alert(this)}); 
/* return: 
* function CustomObject(name, value) { 
this.name = name || "CustomObject"; 
this.value = value || 0; 
this.toString = function () {return "[name:" + this.name + ",value:" + this.value + "]";}; 
} 
*/ 
CustomObject.testFun(); 

此時(shí)如果用實(shí)例來(lái)調(diào)用的話，則會(huì)報(bào)錯(cuò)。如：

復(fù)制代碼代碼如下:

 
var customObject=new CustomObject(); //定義一個(gè)CustomObject實(shí)例 
customObject.testFun();//Error: temp.testFun is not a function 

給實(shí)例增加方法
如果給類型實(shí)例增加方法，則應(yīng)該把方法綁定到類型的prototype上。如

復(fù)制代碼代碼如下:

 
Function.prototype.addMethod=function(methodName,func){ 
if(!this.prototype[methodName]){ 
this.prototype[methodName]=func;//給原型增加方法，此方法會(huì)影響到該類型的實(shí)例上 
} 
return this.prototype;//返回原型，此類型實(shí)例可以進(jìn)行鏈形調(diào)用 
} 
Object.addMethod('testFun',function(){alert(this)}); 
//({toString:function(){return '[Empty Object]'}}).testFun(); //[Empty Object] 
Number.addMethod('testFun',function(){alert(this)}); 
//(5).testFun(); //5 
String.addMethod('testFun',function(){alert(this)}); 
//'test'.testFun(); //'test' 
Boolean.addMethod('testFun',function(){alert(this)}); 
//true.testFun(); //true 
Array.addMethod('testFun',function(){alert(this)}); 
//(['a','b']).testFun(); //a,b 
Date.addMethod('testFun',function(){alert(this)}); 
//new Date().testFun(); //Tue Dec 27 2011 11:20:58 GMT-0800 (Pacific Standard Time) 
function CustomObject(name,value){ 
this.name=name || 'CustomObject'; 
this.value=value || 0; 
this.toString=function(){return '[name:'+this.name+',value:'+this.value+']'} 
} 
CustomObject.addMethod('testFun',function(){alert(this)}); 
var customObject=new CustomObject(); 
customObject.testFun(); //[name:CustomObject,value:0] 

若此時(shí)用類型調(diào)用testFun,則會(huì)報(bào)錯(cuò)。如

復(fù)制代碼代碼如下:

 
Array.addMethod('testFun',function(){alert(this)}); 
//Array.testFun(); //Error: Array.testFun is not a function 
CustomObject.addMethod('testFun',function(){alert(this)}); 
CustomObject.testFun(); //Error: CustomObject.testFun is not a function 