why my code run fail? Uncaught TypeError: Object #<Class> has no method 'startWithTarget'

cocos2d-x JavaScript
#1

below is my code, it’s not worked i don’t know why, is my first time to use cocos2d-html5 framework.

var MyFifthApp = cc.Layer.extend({
    sprite:null,
    spriteFrameNamePrefix:"dargon",
    ctor:function()
    {
        cc.associateWithNative(this, cc.Layer);
        this.init();
    },
    init:function()
    {
        this._super();

        var size = cc.Director.getInstance().getWinSize();

        var cache = cc.SpriteFrameCache.getInstance();
        cache.addSpriteFrames("dargon-hd.plist", "res/dargon-hd.png");

        this.sprite = cc.Sprite.createWithSpriteFrame(cache.getSpriteFrame(this.spriteFrameNamePrefix + "0001.png"));
        this.sprite.setPosition(new cc.Point(size.width/4, size.height/2));

        this.addChild(this.sprite, 0);

        var frames = [];
        for (var i=2;i < 31;i++) {
            var spriteFrame = cache.getSpriteFrame(this.spriteFrameNamePrefix + this.pad(i,4) + ".png");
            frames.push(spriteFrame);
        }

        var animation = cc.Animation.create(frames, 0.5);
        this.sprite.runAction(cc.RepeatForever.create(cc.Animation.create(animation)));

        return this;
    },
    onKeyUp:function(e){},
    pad:function(a, b) {
        return (1e15 + a + "").slice(-b);
    }
});

MyFifthAppScene = cc.Scene.extend({
    onEnter:function(){
        this._super();
        var layer = new MyFifthApp();
        this.addChild(layer);
    }
});