增加监听

worker.js

@@ -26,6 +26,7 @@ const downImage = (function() {
     let url = domains[count % length] + `/${zoom}/${x}/${y}.png`
     let local = `${dirPath}/${zoom}_${x}_${y}.png`
 
+    console.log(url + '请求中')
     return new Promise(resolve => {
       try {
         // 如果30秒都还没完成则直接返回