策略模式的本質，也是設計模式的本質，是將易變化的部分分離出去，不管是物件和物件的行為分離，還是物件和物件表現分離等，都遵循。這是最基本的設計原則。然後把他們組合到一起，生成你需要的，不要管那麼多設計原則，最終的目的是好維護，易讀懂。

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

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();