try to add scheduler btn

renderer.js

@@ -5,14 +5,17 @@ let selectedStore = 'random';
 window.addEventListener('load', () => {
     window.appointment.scanDevices().then((deviceList) => {
         // Make the list
-        let listElement = document.getElementById('device_list');
+        let deviceListSection = document.getElementById('device_list');
+        let deviceNumberInfo = document.createElement("div")
+        deviceNumberInfo.innerHTML = "连接的设备数:" + deviceList.length;
+        deviceListSection.appendChild(deviceNumberInfo);
         for (i = 0; i < deviceList.length; ++i) {
             // Create an item for each one
             let listItem = document.createElement('li');
             // Add the item text
             listItem.innerHTML = deviceList[i].join(" : ");
             // Add listItem to the listElement
-            listElement.appendChild(listItem);
+            deviceListSection.appendChild(listItem);
         }
     })
     document.getElementById("start_book_btn").addEventListener('click', () => {