JavaScript原型对象原理与继承应用详解

function computer(){
   this.name="thinkPad 500";
   this.factory="联想";
   this.price=5000;
   this.size=17;
}
/*
*读取函数中的prototype,默认情况下为空
*/
for( pro in computer.prototype){
   document.write(computer.prototype,"<br>");
}
//没有继承原型对象中属性
var mycomputer=new computer();
for( pro in mycomputer){
   document.write(pro,":",mycomputer[pro],"<br>");
}
computer.prototype.interface="VAG";
//添加原型对象的属性
for( pro in computer.prototype){
   document.write(pro,":",computer.prototype[pro],"<br>");
}
//继承原型对象中属性
var mycomputer=new computer();
for( pro in mycomputer){
   document.write(pro,":",mycomputer[pro],"<br>");
}

<script type="text/javascript">
//定义一个工人
function worker(){
    this.name="";
    this.address="";
}
//定义一个部门经理
function manager(_dept){
    this.dept=_dept;
}
//定义继承关系
manager.prototype=new worker();
//创建计划部门经理
var jh=new manager("计划");
for(pro in jh){
    document.write(pro,":",jh[pro],"<br>");
}
//当前jh有效没有改变原型对象中的值
jh.name="计划部门经理";
jh.address="计划部";
for(pro in jh){
    document.write(pro,":",jh[pro],"<br>");
}
//原型对象中的值没有被修改
var rs=new manager('人事');
for(pro in rs){
    document.write(pro,":",rs[pro],"<br>");
}
//修改原型对象中的值，将会在继承的对象中体现,如果继承类中没有覆盖
manager.prototype.address="成都市";
//覆盖后address的值还是原来的计划
for(pro in jh){
    document.write(pro,":",jh[pro],"<br>");
}
//没有覆盖address的值是成都市
for(pro in rs){
    document.write(pro,":",rs[pro],"<br>");
}
</script>