利用HTML5 Canvas制作一个简单的打飞机游戏

                        if(dataIndex===datas.length){   
                            _this.percent = 100;   
                        }else {   
                            _this.percent = parseInt(dataIndex/datas.length*100);   
                            li.call(_this);   
                        }   
                    }   
                }else {   
                    preLoadImg(datas[dataIndex] , function(){   
                        dataIndex++;   
                        if(dataIndex===datas.length){   
                            _this.percent = 100;   
                        } else {   
                            _this.percent = parseInt(dataIndex/datas.length*100);   
                            li.call(_this);   
                        }   
                    })