策略模式的本质，也是设计模式的本质，是将易变化的部分分离出去，不管是对象和对象的行为分离，还是对象和对象表现分离等，都遵循。这是最基本的设计原则。然后把他们组合到一起，生成你需要的，不要管那么多设计原则，最终的目的是好维护，易读懂。

class Duck{ constructor(id){ = id; } getid(){ console.log(); }

display(){ console.log(“a nomal duck”); } }

class FlyBefavior{ constructor(wings){ this.wings = wings; } fly(){ console.log(fly with ${ this.wings}!); } }

class QuackBefavior{ constructor(sound){ this.sound = sound; } quack(){ console.log(duck make sound,${this.sound}); } }

class swimBefavior{ constructor(){

} swim(){ console.log(“duck swim in water.”); } }

class MallardDuck extends Duck{ constructor(id){ super(id); this.mallfly = new FlyBefavior(“green wings”); this.mallquack = new QuackBefavior(“gua gua gua”); }

fly(){ this.mallfly.fly(); }

quack(){ this.mallquack.quack() }

display(){ console.log(‘yee,a green head duck.’); } }

var m_duck = new MallardDuck(‘002’);

m_duck.display(); m_duck.getid(); m_duck.fly(); m_duck.quack();