This API is available on Firefox OS for internal applications only.
Summary
This method returns a SettingsLock object. This object is used to access and modify all the settings asynchronously and safely.
Each time you use that method, you add the created lock object to an internal list of SettingsLock objects. As long as the current SettingsLock object performs actions against any settings, other SettingsLock objects will not be able to do anything. All their own actions are queued and will be executed at a later time, one object at a time.
Syntax
SettingsManager.createLock();
Example
var lock = navigator.mozSettings.createLock();
Specification
Not part of any specification yet; however, this API will be discussed at W3C as part of the System Applications Working Group.