我也有这样原问题，我是在画背景的时候多添加了句代码

function drawBackground() {

     bgPic.onload = function() {

          ctx2.drawImage(bgPic, 0, 0, canWidth, canHeight);

     }

}

改成：

function drawBackground() {

     ctx2.drawImage(bgPic, 0, 0, canWidth, canHeight);

}

没代码，很难找到问题，我猜你的果实是画的吗？，下载图片资源用context2.drawImage(this.fruitType[i], this.x[i] - this.l[i] * 0.5, this.y[i] - this.l[i]*0.5, this.l[i], this.l[i]);