[JavaScript知识库]typescript学习：class类

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class类

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ES6中的 TS类

公共属性修饰符：

• public：公开的，可读可写，默认修饰符
• private：私有的，不可读不可写
• protected：子类可访问
• readonly: 只能读不能写
• static：静态属性或静态方法（JS中也有）

class Animal {
    public name: string;
	
	constructor(name: string){
		this.name = name
	}
	
	static isAnimal(instantce) {
		return instantce instanceof Animal
	}
	
    eat(){
    	console.log(`${this.name} is eating`)
	}
}

const dog = new Animal('旺财')
dog.eat()            //旺财 is eating
Animal.isAnimal(dog) //true

TS类继承

class Person {
    name: string
    constructor(name: string) {
        this.name = name
    }
    run(): string {
        return `${this.name} is running`
    }
}
let p = new Person('dashen')
p.run()

class Student extends Person {
    constructor(name: string, public age: number) {
        super(name)  //实现继承父类的constructor中name
    }

    study() {
        console.log(`${this.name} is studying`)
    }
}
const s = new Student('小明')
console.log(s)  //{ name: '小明', age: 18 }
s.study()   //小明 is studying

存取器 setter getter

例子：对名字的长度做出限制

class People {
    private _fullname: string = 'tom'

    get fullname(): string {
        return this._fullname
    }

    set fullname(name: string) {
        if (name && name.length < 6) {
            this._fullname = name
        } else {
            console.log(`the length of '${name}' is greater than 6`)
        }
    }
}

let p = new People()
console.log(p.fullname);     //'tom'
p.fullname = 'hello world'   //the length of 'hello world' is greater than 6
p.fullname = 'hello'
console.log(p.fullname);     //'hello'

抽象类

抽象类：原型

1. 使用关键字：abstract，抽象方法只能出现在抽象类里面
2. 提供其他类继承的基类，不能直接被实例化
3. 抽象类的子类必须实现抽象类里面的抽象方法

//定义标准
abstract class Animal {
    name: string = ''
    contructor(name: string) {
        this.name = name
    }

    run() {
        console.log(this.name + 'is running')
    }

    abstract eat(): any
}


class Dog extends Animal {
    constructor(public name: string) {
        super()
    }
    eat() {
        console.log(this.name + 'is eating')
    }
    sleep() {
        console.log(this.name + 'is sleeping')
    }
}
let d: Dog = new Dog('旺财')
d.eat()
d.run()

let d = new Animal('旺财')    // 报错，抽象类不能实例化

let d: Animal = new Dog('旺财')  
d.sleep()  //报错，抽象类没有sleep方法

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