js oop的特性

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

Person.prototype.sayHello = function() {
    console.log(`Hello, my name is ${this.name} and I am ${this.age} years old.`);
};

const person1 = new Person('Alice', 30);
person1.sayHello(); // 输出: Hello, my name is Alice and I am 30 years old.

function Student(name, age, grade) {
    Person.call(this, name, age); // 调用父类构造函数
    this.grade = grade;
}

Student.prototype = Object.create(Person.prototype); // 设置原型链
Student.prototype.constructor = Student; // 修复构造函数指向

Student.prototype.sayGrade = function() {
    console.log(`I am in grade ${this.grade}.`);
};

const student1 = new Student('Bob', 15, 9);
student1.sayHello(); // 输出: Hello, my name is Bob and I am 15 years old.
student1.sayGrade(); // 输出: I am in grade 9.

function Teacher(name, age, subject) {
    Person.call(this, name, age);
    this.subject = subject;
}

Teacher.prototype = Object.create(Person.prototype);
Teacher.prototype.constructor = Teacher;

Teacher.prototype.sayHello = function() {
    console.log(`Hello, I am ${this.name} and I teach ${this.subject}.`);
};

const teacher1 = new Teacher('Charlie', 40, 'Math');
teacher1.sayHello(); // 输出: Hello, I am Charlie and I teach Math.

function Animal(name) {
    this.name = name;
}

Animal.prototype.speak = function() {
    throw new Error('Method "speak" must be implemented.');
};

function Dog(name) {
    Animal.call(this, name);
}

Dog.prototype = Object.create(Animal.prototype);
Dog.prototype.constructor = Dog;

Dog.prototype.speak = function() {
    console.log(`${this.name} barks.`);
};

const dog1 = new Dog('Rex');
dog1.speak(); // 输出: Rex barks.