[JavaScript知识库]TypeScript单例模式、代理模式、观察者模式、工厂模式dome

一、单例模式

1.预加载

class SoundManager{
    static Instance = new SoundManager();
    name: string = '单例'
    private constructor() { }
}
console.log(SoundManager.Instance.name)

2.懒加载

// ts访问修饰符
// 1、public: 公开的，默认 任何对象在任何地方都可以进行访问
// 2、private： 私有的， 只能在当前类中进行访问
// 3、 protected： 受保护的，这能在当前类或者子类中进行访问
class ISoundManager {
    private static instance: ISoundManager = null;
    private constructor() { }
    name: string = '懒加载';
    static Instance() {
        if (!ISoundManager.instance) {
            ISoundManager.instance = new ISoundManager();
        }
        return ISoundManager.instance;
    }
}
console.log(ISoundManager.Instance().name)

二、 代理模式

interface ICalc {
    calc(num1, num2): number;
}
class Npc1 implements ICalc{
    calc(num1, num2) {
        return num1 + num2;
    }
}
class Npc2 implements ICalc{
    calc(num1, num2) {
        return num1 - num2;
    }
}
class Person {
    delegate: ICalc;
    //计算数字
    GetNum(num1, num2) {
        //拿到num1 和12计算后的结果
        let num = this.delegate.calc(num1, num2);
        console.log(num)
    }
}
let person = new Person();
person.delegate = new Npc2();
person.GetNum(3, 4);
person.delegate = new Npc1();
person.GetNum(3, 4);

三、观察者模式

interface IObserverf{
    nameChanged(oldName,newName);
}
class Person{
    private _name: string = '嘻嘻';
    observers: Array<IObserverf> = new Array<IObserverf>();
    set name(value: string) {
        let oldName: string = this._name;
        this._name = value;
        //发生变化，便利观察者数组，给所有的观察者发消息
        for (let observer of this.observers) {
            observer.nameChanged(oldName,this._name);
        }
    }
    get name(){
        return this._name;
    }
}
class Test implements IObserverf {
    nameChanged(oldName: string,newName: string) {
        document.write("监听到变化，名字" + oldName + "变为" + newName);
    }
}
let person = new Person();
let test = new Test();
person.observers.push(test);
person.name = "哈哈";

四、工厂模式

enum CarType{
    Bmw,
    Audi,
    Benz
}
class Car {
    name: string;
    static Create(carType: CarType): Car {
        let car: Car;
        switch (carType) {
            case CarType.Audi:
                car = new Audi();
                break;
            case CarType.Benz:
                car = new Benz();
                break;
            case CarType.Bmw:
                car = new Bmw();
                break;
        }
        return car;
    }
}
class Bmw extends Car {}
class Benz extends Car {}
class Audi extends Car {}
let bmw = Car.Create(CarType.Bmw);
let bgenz = Car.Create(CarType.Benz);
let audi = Car.Create(CarType.Audi);
console.log(bmw,bgenz,audi)