代码如下，在 onLoaded 里注册的开始游戏按钮事件，点击执行gameInit添加hero,这时候界面没有东西；当三秒后游戏结束，点重新开始，飞机才出来

 function onLoaded() {
        start = new GameStartUI();
        start.btn_start.on(Event.MOUSE_UP,this,gameInit)
        Laya.stage.addChild(start);
    }

    function gameInit() {
        map = new GameBgUI();
        Laya.stage.addChild(map);

        play = new GamPlayUI();
        Laya.stage.addChild(play);

        hero = new Hero("hero", 25)
        hero.pos(100,200)
        Laya.stage.addChild(hero)

        Laya.timer.once(3000, this, gameOver)
    }

    function gameOver() {
        map.removeSelf()
        play.removeSelf()
        over = new GameOverUI()
        over.txt_score.text = "25"
        over.btn_restart.on(Event.MOUSE_UP,this,gameInit)
        Laya.stage.addChild(over);
    }

hero类：

(function() {
    function Hero(type, hp) {

        Hero.__super.call(this);
        this.fly();
    }
    Laya.class(Hero,"Hero", Air);
    var _proto = Hero.prototype;

    _proto.fly = function() {
        this.playAction("fly")
    }
})();

air类：

(function() {
    function Air(type, hp) {
        this.hp = hp;
        this.type = type;
        this.body = null;
        Air.__super.call(this);
        this.init();
    }
    Laya.class(Air,"Air", laya.display.Sprite);

    var _proto = Air.prototype;

    _proto.init = function() {
        if(this.body == null) {
            this.body = new laya.display.Animation();
            this.addChild(this.body)
            this.body.loadAnimation("GameRole.ani")
        }
    }

    _proto.playAction = function(action){
        //如果是重复的动作 不执行
        if(this.action == action)return;
        this.action = action;
        this.body.play(0, true,this.type+"_" + this.action);
    }
})();