老师，这里为啥会有undefined

来源：2-1 Class 是什么

张小阳_

2022-10-31 23:00:56

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        class Person {
            constructor(name, age) {    // 实例化时执行构造方法，所以必须有构造方法，但可以不写出来
                console.log('实例化时执行构造函数');
                this.name = name;
                this.age = age;
            }
            speak() {
                console.log('hello');
            }
        }

        const zs = new Person('zhangSan', 20);
        const ls = new Person('liSi', 29);
        console.log(zs);
        console.log(zs.name);
        console.log(zs.age);
        console.log(ls.speak());
        console.log(zs.speak());
        console.log(zs.speak() === ls.speak());
    </script>
</body>

</html>