<script>

    class user{

        constructor(name,age){

            this.name=name;

            this.age=age;

        }

        showName(){

            alert(this.name)

        }

        showAge(){

            alert(this.age)

        }

    }

    var zhangsan=new user('aaaa',18);

    zhangsan.showName()

    zhangsan.showAge()

</script>