原型继承
```<script>
//Person人类 - 父类
function Person() {
this.name = 'jack'
}
Person.prototype.eat = function () {
console.log('吃饭')
}
//Student学生类 -子类
function Student() {
this.num = 1001
}
//原型继承 - 父类实例对象赋值给子类原型
Student.prototype = new Person()
let s1 = new Student()
s1.eat()
console.log(s1.name);
</script>