Reload spots/alerts on visibility change. Closes #89

webassets/js/spotsbandsandmap.js

@@ -49,4 +49,12 @@ function filtersUpdated() {
 function toggleDarkMode() {
     enableDarkMode($("#darkMode")[0].checked);
     saveSettings();
-}
+}
+
+// Reload spots on becoming visible. This forces a refresh when used as a PWA and the user switches back to the PWA
+// after some time has passed with it in the background.
+addEventListener("visibilitychange", (event) => {
+    if (!document.hidden) {
+        loadSpots();
+    }
+});