Integrating with the Windows 8 environment - Build Windows 8 Apps with HTML5 and JavaScript - page 228

function _saveToSettings() {
localSettings.values["defaultPriority"] = that.defaultPriority;
};
return that;
});
TodoList.settings = new TodoListSettings();
Important The exact position of this code is not particularly important, so long as it is
preceded by the definition of the TodoList.Priority object. It is suggested that you add this
code at top of the file right after the definition of the TodoList object and make it follow
only the definition of the TodoList.Priority object.
The TodoListSettings object is an object with one property—the defaultPriority property. This is
because in the current example you are going to have only one customizable option—the default
priority level of any newly created task. So far, you had it default to Normal; now you want to make
this value configurable on a per user basis.
However, the TodoListSettings object is not limited to defining the defaultPriority property; it also
features a couple of load/save methods. The idea is that the TodoListSettings object makes itself
responsible for loading and saving its content to a persistent store without requiring more than a
plain call to the load or save method. The details of how settings are persisted or retrieved are not
known outside the boundaries of the object.
In addition, an instance of the TodoListSettings object is created during the initialization of the
application and is made available through the TodoList.settings object. The bottom line is that in this
way, the application loads its settings from a persistent store at startup and these settings are globally
available for the entire lifecycle.
persisting application settings
Windows 8 provides applications with a system dictionary where data can be saved in pairs—a
unique ID and a corresponding value. Values can only be primitive types, such as strings and integers.
The system object that provides access to this data store is Windows.Storage.ApplicationData.current.
localSettings . The object exposes a values property that is the actual dictionary where data is stored.
For example, the default priority level set for the application is stored in an entry whose ID
matches the property name.
var priority = localSettings.values["defaultPriority"];