在本例中，我们将展示如何使用 prototype 属性来向对象添加属性：

<script type="text/javascript">function employee(name,job,born){this.name=name;this.job=job;this.born=born;}var bill=new employee("Bill Gates","Engineer",1985);employee.prototype.salary=null;bill.salary=20000;document.write(bill.salary);</script>

js prototype 添加属性对象