一、类的定义

二、对象的创建

class Person{
    id:number;
    name:string;
    age:number = 18;


    constructor(id:number,name:string)
    {
        this.id = id;
        this.name = name;
    }

    introduce():string{
        return `hello,I am ${this.name},and I am ${this.age} years old.`
    }
}

let person = new Person(1,'zhangsan');

console.log(person)

三、静态成员

声明静态成员 使用static关键字，静态成员隶属于类本身，而不属于某个对象实例

class Constants{
    static count:number = 1;
}

class Utils{
    static toLowerCase(str:string){
        return str.toLowerCase();
    }
}

console.log(Constants.count);

console.log(Utils.toLowerCase("Hello World"))

四、类的继承

继承是面向对象编程中的重要机制，允许一个类(子类或派生类)继承另一个(父类或基类)的属性和方法。子类可以直接使用父类的特性，并根据需要添加新的特性或覆盖现有的特性。

class Person{
    id:number;
    name:string;
    age:number = 18;


    constructor(id:number,name:string)
    {
        this.id = id;
        this.name = name;
    }

    introduce():string{
        return `hello,I am ${this.name},and I am ${this.age} years old.`
    }
}

class Student extends Person{


    classNumber:string;

    constructor(id:number,name:string,classNumber:string)
    {
        super(id,name);
        this.classNumber = classNumber;
    }

    introduceSTU():string{
        return `hello,I am ${this.name},and I am ${this.age} years old.I am a student`
    }
}

let student = new Student(1,'zhangsan','aaa');

console.log(student.introduceSTU());

4.1 访问修饰符

主要用于控制类成员的可访问性

 五、接口

5.1 接口的定义

通常情况下接口只会包含属性和方法的声明，而不包含具体的实现细节，具体的细节由其实现类完成

interface Person{
    id:number;
    name:string;
    age:number;

    introduce():void;
}

5.2 接口的实现

interface Person{
    id:number;
    name:string;
    age:number;

    introduce():void;
}

class Stu implements Person{
    id:number;

    name:string;

    age:number;

    constructor(id:number,name:string,age:number){
        this.id = id;
        this.name = name;
        this.age = age;
    }

    introduce():void{
        console.log("Hello zzm")
    }
}


let s1 = new Stu(1,'zzm',1);

console.log(s1.introduce())

六、多态

多态可以使同一类型的对象具有不同的行为

interface Person{
    id:number;
    name:string;
    age:number;

    introduce():void;
}

class Stu implements Person{
    id:number;

    name:string;

    age:number;

    constructor(id:number,name:string,age:number){
        this.id = id;
        this.name = name;
        this.age = age;
    }

    introduce():void{
        console.log("Hello stu")
    }
}

class Tea implements Person{
    id:number;
    name:string;
    age:number;

    constructor(id:number,name:string,age:number){
        this.id = id;
        this.name = name;

        this.age = age;
    }

    introduce():void{
        console.log("Hello,tea")
    }
}


let s1 = new Stu(1,'zzm',1);
let t1 = new Tea(1,"zzm",1);

s1.introduce();
t1.introduce();