js继承的实现代码_javascript技巧

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);
}
}

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


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