W3C has published the first working draft of the Web Alarms API Specification. The API gives developers access to device alarm settings for applications that need to notify the user.

Examples of applications suggested by W3C include alarm clocks, calendars or auto-updates. The system level API would be used to schedule a notification or to start an application at a specific time.

The Alarm API supports the following features:

• Web applications can add multiple alarms and get a returned ID for each of them.
  
  
• The returned ID is unique (within the application origin) and can be used to specify and remove the added alarm.
  
  
• Web applications can pass a customized JSON object data to describe more details about each alarm setting.
  
  
• Web applications can only access their own alarms.
  
  
• When the alarm goes off, an alarm event will be fired.
  
  
• All the alarms that have been added can be automatically restored after rebooting the system.
  
  
• Alarm API actually does more than setTimeout because it can actively wake up the system from sleeping.
  
  
• Whenever the system clock or timezone is adjusted at run-time, all the saved alarms will be rescheduled.

Using the API, you’d be able to add an alarm that respects the local time zone to a device using code such as

 var alarmId2; 
 var request = navigator.alarms.add(
   new Date("June 29, 2012 07:30:00"),
     "respectTimezone",
       { mydata: "foo" }); 

 request.onsuccess = function (e) {
                alarmId2 = e.target.result; };

 request.onerror = function (e) {
                alert(e.target.error.name); };