diff --git a/index.html b/index.html
index 22efbb4..3225965 100644
--- a/index.html
+++ b/index.html
@@ -32,11 +32,11 @@
 
 // http://api.amap.com/javascript/index
 // http://api.amap.com/javascript/example
-var mapObj;
+let mapObj;
 
 function addBuildings(){  
     if (typeof(Worker) !== "undefined") {  
-        var buildings = new AMap.Buildings(); //实例化3D楼块图层  
+        let buildings = new AMap.Buildings(); //实例化3D楼块图层  
         buildings.setMap(mapObj);//在map中添加3D楼块图层  
     } else {
         // document.getElementById("info").innerHTML="对不起，运行该示例需要浏览器支持HTML5！";  
@@ -47,17 +47,17 @@ function addBuildings(){
 //添加带文本的点标记覆盖物  
 function addMarker(){   
     //自定义点标记内容     
-    var markerContent = document.createElement("div");  
+    let markerContent = document.createElement("div");  
     markerContent.className = "markerContentStyle";  
       
     //点标记中的图标  
-    var markerImg= document.createElement("img");  
+    let markerImg= document.createElement("img");  
      markerImg.className="markerlnglat";  
      markerImg.src="https://webapi.amap.com/images/0.png";     
      markerContent.appendChild(markerImg);  
        
      //点标记中的文本  
-     var markerSpan = document.createElement("span");  
+     let markerSpan = document.createElement("span");  
      markerSpan.innerHTML = "我是自定义样式的点标记哦！";  
      markerContent.appendChild(markerSpan);  
      marker = new AMap.Marker({  
@@ -85,14 +85,14 @@ function mapInit(){
 
     // https://github.com/unixcrh/DOUBANTONGCHENG/blob/master/DouBanTongCheng/ContentVC.m
     // https://developers.douban.com/wiki/?title=event_v2
-    var doubanEvents = [
+    let doubanEvents = [
         "https://api.douban.com/v2/event/list?loc=shanghai&type=music&max-results=30&callback=?",
         "https://api.douban.com/v2/event/list?loc=shanghai&type=drama&max-results=30&callback=?",
         "https://api.douban.com/v2/event/list?loc=shanghai&type=film&max-results=30&callback=?",
         "https://api.douban.com/v2/event/list?loc=shanghai&type=exhibition&max-results=30&callback=?",
     ];
     // http://fontawesome.io/icons/
-    var doubanIcons = [
+    let doubanIcons = [
         '<i class="fa fa-music" aria-hidden="true"></i>',
         '<i class="fa fa-magic" aria-hidden="true"></i>',
         '<i class="fa fa-film" aria-hidden="true"></i>',
@@ -100,20 +100,22 @@ function mapInit(){
     ];
 
     // http://www.flaticon.com/
-    var doubanFlatIcons = [
+    let doubanFlatIcons = [
         'media/music-player.png',
         'media/theater.png',
         'media/camera.png',
         'media/college.png',
     ];
+
+    let fail_to_access_douban = false;
     doubanEvents.forEach(function(doubanEvent, i) {
         $.getJSON(doubanEvent)
             .done(function(json){
                 //response json are now in the json variable
                 // console.log(json);
                 json.events.reverse().forEach(function(ev, j) {
-                    var geo = ev.geo.split(' ');
-                    var marker = new AMap.Marker({
+                    let geo = ev.geo.split(' ');
+                    let marker = new AMap.Marker({
                         map:        mapObj,
                         position:   new AMap.LngLat(geo[1], geo[0]),
                         icon:       doubanFlatIcons[i],
@@ -145,8 +147,12 @@ function mapInit(){
                     });
                 });
             })
-            .fail(function() {
-                console.log('Can not use douban api');
+            .fail(function( jqxhr, textStatus, error ) {                
+                if (!fail_to_access_douban) {
+                    let err = textStatus + ", " + error;
+                    alert( "Access douban failed: " + err );
+                }
+                fail_to_access_douban = true;
             }); 
     });   
 }