学步园

<script>
function Person (name, age) {
    this.name = name;
    this.age = age;
}

Person.prototype.sayHi = function (){
    alert(this.name+'=='+ this.age)
}

function student(name,age) {
    Person.apply(this, [name, age])
}
student.prototype = Person.prototype;
var stu = new student("zhang1",221);
stu.sayHi()
</script>