cocos2d js 如何动态加载外部图片

官网没有具体例子，只有看api，研究成果如下

        var that = this;        var url = "http://xxxxxx";        cc.loader.loadImg(url, null, function(err,img){        var logo  = new cc.Sprite(img);         that.addChild(logo);        logo.x = size.width / 2;        logo.y = size.height / 2;        });