Accessibility checks are now made before trying to access local storage. Fixes #174.

src/web/App.js

@@ -240,7 +240,7 @@ App.prototype.initialiseSplitter = function() {
 App.prototype.loadLocalStorage = function() {
     // Load options
     let lOptions;
-    if (localStorage.options !== undefined) {
+    if (this.isLocalStorageAvailable() && localStorage.options !== undefined) {
         lOptions = JSON.parse(localStorage.options);
     }
     this.manager.options.load(lOptions);
@@ -256,13 +256,17 @@ App.prototype.loadLocalStorage = function() {
  * If the user currently has no saved favourites, the defaults from the view constructor are used.
  */
 App.prototype.loadFavourites = function() {
-    let favourites = localStorage.favourites &&
-        localStorage.favourites.length > 2 ?
-        JSON.parse(localStorage.favourites) :
-        this.dfavourites;
+    let favourites;
 
-    favourites = this.validFavourites(favourites);
-    this.saveFavourites(favourites);
+    if (this.isLocalStorageAvailable()) {
+        favourites = localStorage.favourites && localStorage.favourites.length > 2 ?
+            JSON.parse(localStorage.favourites) :
+            this.dfavourites;
+        favourites = this.validFavourites(favourites);
+        this.saveFavourites(favourites);
+    } else {
+        favourites = this.dfavourites;
+    }
 
     const favCat = this.categories.filter(function(c) {
         return c.name === "Favourites";
@@ -306,6 +310,15 @@ App.prototype.validFavourites = function(favourites) {
  * @param {string[]} favourites - A list of the user's favourite operations
  */
 App.prototype.saveFavourites = function(favourites) {
+    if (!this.isLocalStorageAvailable()) {
+        this.alert(
+            "Your security settings do not allow access to local storage so your favourites cannot be saved.",
+            "danger",
+            5000
+        );
+        return false;
+    }
+
     localStorage.setItem("favourites", JSON.stringify(this.validFavourites(favourites)));
 };
 
@@ -503,6 +516,22 @@ App.prototype.setCompileMessage = function() {
 };
 
 
+/**
+ * Determines whether the browser supports Local Storage and if it is accessible.
+ * 
+ * @returns {boolean}
+ */
+App.prototype.isLocalStorageAvailable = function() {
+    try {
+        if (!localStorage) return false;
+        return true;
+    } catch (err) {
+        // Access to LocalStorage is denied
+        return false;
+    }
+};
+
+
 /**
  * Pops up a message to the user and writes it to the console log.
  *

src/web/ControlsWaiter.js

@@ -254,6 +254,15 @@ ControlsWaiter.prototype.loadClick = function() {
  * Saves the recipe specified in the save textarea to local storage.
  */
 ControlsWaiter.prototype.saveButtonClick = function() {
+    if (!this.app.isLocalStorageAvailable()) {
+        this.app.alert(
+            "Your security settings do not allow access to local storage so your recipe cannot be saved.",
+            "danger",
+            5000
+        );
+        return false;
+    }
+
     const recipeName = Utils.escapeHtml(document.getElementById("save-name").value);
     const recipeStr  = document.querySelector("#save-texts .tab-pane.active textarea").value;
 
@@ -283,6 +292,8 @@ ControlsWaiter.prototype.saveButtonClick = function() {
  * Populates the list of saved recipes in the load dialog box from local storage.
  */
 ControlsWaiter.prototype.populateLoadRecipesList = function() {
+    if (!this.app.isLocalStorageAvailable()) return false;
+
     const loadNameEl = document.getElementById("load-name");
 
     // Remove current recipes from select
@@ -313,6 +324,8 @@ ControlsWaiter.prototype.populateLoadRecipesList = function() {
  * Removes the currently selected recipe from local storage.
  */
 ControlsWaiter.prototype.loadDeleteClick = function() {
+    if (!this.app.isLocalStorageAvailable()) return false;
+
     const id = parseInt(document.getElementById("load-name").value, 10);
     const rawSavedRecipes = localStorage.savedRecipes ?
         JSON.parse(localStorage.savedRecipes) : [];
@@ -328,6 +341,8 @@ ControlsWaiter.prototype.loadDeleteClick = function() {
  * Displays the selected recipe in the load text box.
  */
 ControlsWaiter.prototype.loadNameChange = function(e) {
+    if (!this.app.isLocalStorageAvailable()) return false;
+
     const el = e.target;
     const savedRecipes = localStorage.savedRecipes ?
         JSON.parse(localStorage.savedRecipes) : [];

src/web/OperationsWaiter.js

@@ -229,7 +229,7 @@ OperationsWaiter.prototype.editFavouritesClick = function(e) {
         filter: ".remove-icon",
         onFilter: function (evt) {
             const el = editableList.closest(evt.item);
-            if (el) {
+            if (el && el.parentNode) {
                 $(el).popover("destroy");
                 el.parentNode.removeChild(el);
             }

src/web/OptionsWaiter.js

@@ -87,7 +87,9 @@ OptionsWaiter.prototype.switchChange = function(e, state) {
     const option = el.getAttribute("option");
 
     this.app.options[option] = state;
-    localStorage.setItem("options", JSON.stringify(this.app.options));
+
+    if (this.app.isLocalStorageAvailable())
+        localStorage.setItem("options", JSON.stringify(this.app.options));
 };
 
 
@@ -102,7 +104,9 @@ OptionsWaiter.prototype.numberChange = function(e) {
     const option = el.getAttribute("option");
 
     this.app.options[option] = parseInt(el.value, 10);
-    localStorage.setItem("options", JSON.stringify(this.app.options));
+
+    if (this.app.isLocalStorageAvailable())
+        localStorage.setItem("options", JSON.stringify(this.app.options));
 };
 
 
@@ -117,7 +121,9 @@ OptionsWaiter.prototype.selectChange = function(e) {
     const option = el.getAttribute("option");
 
     this.app.options[option] = el.value;
-    localStorage.setItem("options", JSON.stringify(this.app.options));
+
+    if (this.app.isLocalStorageAvailable())
+        localStorage.setItem("options", JSON.stringify(this.app.options));
 };
 
 

src/web/html/index.html

@@ -35,7 +35,11 @@
             "use strict";
 
             // Load theme before the preloader is shown
-            document.querySelector(":root").className = (JSON.parse(localStorage.getItem("options")) || {}).theme;
+            try {
+                document.querySelector(":root").className = (JSON.parse(localStorage.getItem("options")) || {}).theme;
+            } catch (err) {
+                // LocalStorage access is denied by security settings
+            }
 
             // Define loading messages
             const loadingMsgs = [