本文介绍了一个使用JavaScript实现构造函数继承的例子。通过BaseClass和SonClass两个类展示了如何在子类中继承父类的方法和属性，并对原型链上的属性进行覆盖及扩展。
JS.js文件：
function BaseClass()
{
this.name="BaseClass"; //this.prototype.Height="1.5米"; 错误写法 BaseClass.prototype.Height="1.5米"; this.Width="2米"; this.Weight="1吨";
this.say=function(){ return "my name is "+this.name+",Height:"+this.Height+",Width:"+this.Width+",Weight:"+this.Weight;
}
}function SonClass(){ this.base=BaseClass; this.base(); this.Weight="2吨"; this.Color="red"; this.Title="SonClass"; this.loudsay=function(){ return "my name is "+this.Title+",Height:"+this.Height+",Width:"+this.Width+",Weight:"+this.Weight+",Color:"+this.Color; }}
SonClass.prototype.Speed="100"; SonClass.prototype.run=function(){ return "my name is "+this.Title+",Height:"+this.Height+",Width:"+this.Width+",Weight:"+this.Weight+",Color:"+this.Color+",Speed:"+this.Speed;}HTML：
<html> <head> <title></title> <script src=jS.js type="text/javascript"></script> <script language=javascript> //BaseClass baseclass = new BaseClass();错误写法 var baseclass = new BaseClass(); alert(baseclass.name); //Base alert(baseclass.say());//my name is BaseClass,Height:1.5米,Width:2米,Weight:1吨 var Son = new SonClass(); alert(Son.say());//my name is BaseClass,Height:undefined,Width:2米,Weight:2吨 alert(Son.loudsay());//my name is SonClass,Height:undefined,Width:2米,Weight:2吨,Color:red alert(Son.run());//my name is SonClass,Height:undefined,Width:2米,Weight:2吨,Color:red,Speed:100 SonClass.prototype.Height="2.5米"; alert(Son.run());//my name is SonClass,Height:2.5米,Width:2米,Weight:2吨,Color:red,Speed:100 </script> </head> <body > </body></html>
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