yichael_boxingtutorial/assets/Scripts/Games/CountDown.js

cc.Class({
    extends: cc.Component,

    properties: {

    },
    countDown(callback)
    {
        this.node.opacity = 255;
        this.callback = callback;
        this.currentCount = 3;
        this.counting();
    },
    counting()
    {
        let Self = this;
        cc.loader.loadRes("Audios/Game/Nums/"+this.currentCount, cc.AudioClip, (err, audioClip)=> {

            Self.node.getComponent(cc.Label).string = Self.currentCount;

            Self.currentAudio = cc.audioEngine.play(audioClip, false, 1);
            cc.audioEngine.setFinishCallback(Self.currentAudio, function () {
                if(Self.currentCount == 1)
                {
                    Self.currentCount = 3;
                    Self.node.opacity = 0;
                    Self.callback();
                    return;
                }
                Self.currentCount--;
                Self.counting();
            });

        });
    }
});