1.工厂模式

class Factory{createProduct(name){return new Product(name);}
}
class Product{constructor(name){this.name=name;}display(){console.log(`product:${this.name}`);}
}//使用
const factory=new Factory();
const p1=factory.createProduct('P1');
const p2=factory.createProduct('P2');
p1.display()
p2.display()

2.单例模式

class Singleton{static instance=null;constructor(){if(Singleton.instance){return Singleton.instance}Singleton.instance=this;}
}//使用
const instance1=new Singleton()
const instance2=new Singleton()

3.观察者模式

class Subject{constructor(){this.observers=[];}addObserver(observer){this.observers.push(observer);}removerObserver(observer){this.observers=this.observers.filter(obs=>obs!==observer);}notifyObserver(){this.observers.forEach(obs=>obs.update());}
}class Observer{constructor(name){this.name=name;}update(){console.log(`Observer ${this.name} has been notified`);}
}
//使用
const subject=new Subject();
const observer1=new Observer('1');
const observer2=new Observer('2');
subject.addObserver(observer1);
subject.addObserver(observer2);
subject.notifyObserver();

4.发布订阅模式

class Broker{constructor(){this.subscribers=[];this.state=0;}subscribe(subscriber){this.subscribers.push(subscriber);}setState(state){this.state=state;this.publish();}getState(){return this.state;}publish(){this.subscribers.forEach(sub=>sub.update());}
}class Publisher{constructor(){}changeState(broker,state){broker.setState(state);}
}class Subscriber{constructor(name,broker){this.name=name;this.broker=broker;this.broker.subscribe(this);}update(){console.log(`${this.name}:${this.broker.getState()}`);}
}
//使用
const broker=new Broker();
const publish=new Publisher();
const subscribe1=new Subscriber('s1',broker);
const subscribe2=new Subscriber('s2',broker);
publish.changeState(broker,1);