JavaScript 实现继承的 extendf 方法与测试示例

JavaScript 继承实现概述

base.js --继承的实现==========================

【注】：继承后，如果父类是一个类，则会继承其属性，方法（包括用prototype声明的），静态方法，否则只有属性和方法。

 
Object.prototype.extendf= function (a,b){
if(!a||!b) return;
var fa = typeof a=="function";
var fb = typeof b=="function";
var cha = function(a,b){
for(var c in b){
if(a[c]==undefined)//子类重写
a[c]=b[c];
} 
return a;//返回继承后的对象
} 
if(fa&&fb){
b.apply(this,a.arguments);
cha(a,b);
this["base"] =new b;//通过base访问父类
return cha(this,b.prototype);
} 
}else if(!fa&&fb){
cha(a,new b);
a["base"]= new b;
return cha(a,b);
}else if(fa&&!fb){
cha(a,b);
this["base"]=b;
return cha(this,b);
}else if(!fa&&!fb){
a["base"]=b;
return cha(a,b);
} 
} 

继承方法 extendf 的实现细节

测试页：用法

 
<html>
<head>
<script type="text/javascript" src="base.js"></script>
<script type="text/javascript">
var car2 = {
name:"轿车【父类】",
price:"几万【父类】",
start : function(){
alert(this.name+" 已启动2！【父类}");
}, 
run : function(){
alert(this.name+" 在行驶当中2。。。【父类}");
}, 
stop: function(){
alert(this.name+" 已停止2！【父类}");
}, 
remark: function(){return "【父类】2我是一辆 "+this.name+"；价值 "+this.price;}
// this.remark = "我是一辆 "+this.name+"；价值 "+this.price;
} 
//car2.prototype.extra = function(ext){
// return this.name+" 的关税2是："+ext;
//} 
car2.protect = "【父类】2保护的";
car2.noExtra = function(){
return car.protect+" 不交关税2【父类}";
} 
var car = function(name,price){
this.name=name||"轿车 [父类]";
this.price=price||"几万[父类]";
this.start = function(){
alert(this.name+" 已启动！[父类]");
}; 
this.run = function(){
alert(this.name+" 在行驶当中。。。[父类]");
}; 
this.stop= function(){
alert(this.name+" 已停止！[父类]");
}; 
this.remark = function(){return "[父类]我是一辆 "+this.name+"；价值 "+this.price;};
// this.remark = "我是一辆 "+this.name+"；价值 "+this.price; //注意，这样做 name 和price 将得不到传参，故注释
} 
car.prototype.extra = function(ext){
return this.name+" 的关税是[父类]："+ext;
} 
car.protect = "[父类]保护的";
car.noExtra = function(){
return car.protect+" 不交关税[父类]";
} 
var BMW = function(){
this.extendf(BMW,car);
this.name = "BMW【子类}";
this.start=function(){
alert(this.name+"专属 启动装置！");
}; 
return ("this.name1="+this.name);
} 
var BMW2 = function(){
this.extendf(BMW2,car2);
this.name = "宝马终极2号【子类}";
this.start=function(){
alert(this.name+" 专属 启动装置2号未来！");
}; 
return ("this.name1="+this.name);
} 
var bensi = {
name:"bensi",
price:"130万",
start:function(){
alert(this.name+" 华丽启动！");
}, 
stop:function(){
alert(this.name+" 专用刹车停止！");
} 
} 
bensi.noExtra=function(){
return "谁敢收税？";
} 
var autuo = {
name:"autuo【子类}",
price:"1万",
stop:function(){
alert(this.name+" 奥拓失灵了！");
} 
} 
function ChangAn(){
this.extendf(ChangAn,car);
// this.name = "CHANGAN【子类}";
this.run=function(){
alert(this.name+" 走的有点慢。。。");
} 
} 
var ftest = function(){
var tb = new BMW("宝马","70万");
testRun(tb);
alert(BMW.noExtra());
} 
var ftest2 = function(){
var tb = bensi//("奔驰","120万");
tb.extendf(bensi,car);
testRun(bensi);
alert(bensi.noExtra());
} 
var ftest3 = function(){
var tb = new ChangAn("长安[传参]","5万");
testRun(tb);
alert(ChangAn.noExtra());
} 
var ftest4 = function(){
var tb = autuo
tb.extendf(autuo,car2);
testRun(tb);
alert(autuo.noExtra());
} 
var ftest5 = function(){
var tb = autuo
tb.extendf(autuo,bensi);
alert(tb.name);
tb.start();
tb.stop();
alert(autuo.noExtra());
} 
var ftest6 = function(){
var tb = new BMW2("宝马2号","65万");
var scar = document.getElementById("showcar");
scar.innerHTML = tb.remark();
alert(tb.name);
tb.start();
tb.stop();
alert(BMW2.noExtra());
} 
//测试输出
function testRun(tb){
var scar = document.getElementById("showcar");
if(!scar) return false;
scar.innerHTML = tb.remark();
tb.base.start();
tb.start();
tb.base.run();
tb.run();
tb.base.stop();
tb.stop();
alert(tb.extra("1万"));//父类为Object时这个会出错，因为父类本身就没有
} 
</script>
</head>
<body>
js测试：
<input type = "button" value = "宝马" onclick = "ftest()" >
<input type = "button" value = "奔驰" onclick = "ftest2()" >
<input type = "button" value = "长安" onclick = "ftest3()" >
<input type = "button" value = "奥拓" onclick = "ftest4()" >
<input type = "button" value = "奔驰类的奥拓" onclick = "ftest5()" >
<input type = "button" value = "宝马2号" onclick = "ftest6()" >
<div id = "showcar"></div>
</body>
</html>

ps：没有注意到性能问题，往大家改善

想只用一个参数，不知道大家有没有办法？

嵌套类 没试过。