function employee()
{
//this.salary=123;
//employee.prototype.salary=333;
employee.salary=222;
}
employee.salary=222;
var bill=new employee();
alert(employee.salary);//222
alert(bill.salary);//undefined?????为什么不是222
bill是employee的实例。employee.prototype.salary才能由bill访问。
employee.salary=222; 只是说 salary属性是employee对象的, 这个属性不会继承