catch SecurityError with localStorage, fixes #47

js/Map.js

@@ -60,7 +60,7 @@ BR.Map = {
         map = new L.Map('map', {
             worldCopyJump: true
         });
-        if (!map.restoreView()) {
+        if (!BR.Util.localStorageAvailable() || !map.restoreView()) {
             map.setView([50.99, 9.86], 6);
         }
         map.attributionControl.addAttribution(

js/Util.js

@@ -29,6 +29,26 @@ BR.Util = {
           msg = xhr.status + ': ' + xhr.statusText;
         }
         return new Error(msg);
-    }
+    },
 
+    // check if localStorage is available, especially for catching SecurityError
+    // when cookie settings are blocking access (Chrome, Pale Moon, older Firefox)
+    // 
+    // see also https://github.com/Modernizr/Modernizr/blob/master/feature-detects/storage/localstorage.js
+    // 
+    // https://developer.mozilla.org/en-US/docs/Web/API/Web_Storage_API/Using_the_Web_Storage_API#Testing_for_support_vs_availability
+    // by Mozilla Contributors, with modifications; 
+    // Any copyright is dedicated to the Public Domain. http://creativecommons.org/publicdomain/zero/1.0/
+    localStorageAvailable: function() {
+        try {
+            var storage = window.localStorage,
+                x = '__storage_test__';
+            storage.setItem(x, x);
+            storage.removeItem(x);
+            return true;
+        }
+        catch(e) {
+            return false;
+        }
+    }
 };

js/control/OpacitySlider.js

@@ -7,7 +7,7 @@ BR.OpacitySlider = L.Control.extend({
     onAdd: function (map) {
         var container = L.DomUtil.create('div', 'leaflet-bar control-slider'),
             input = $('<input id="slider" type="text"/>'),
-            item = localStorage.opacitySliderValue,
+            item = BR.Util.localStorageAvailable() ? localStorage.opacitySliderValue : null,
             value = item ? parseInt(item) : BR.conf.defaultOpacity * 100,
             minOpacity = (BR.conf.minOpacity || 0) * 100;
 
@@ -39,7 +39,9 @@ BR.OpacitySlider = L.Control.extend({
         }).on('slide slideStop', { self: this }, function (evt) {
             evt.data.self.options.callback(evt.value / 100);
         }).on('slideStop', function (evt) {
+            if (BR.Util.localStorageAvailable()) {
                 localStorage.opacitySliderValue = evt.value;
+            }
 
             // When dragging outside slider and over map, click event after mouseup
             // adds marker when active on Chromium. So disable click (not needed)