Is it possible to make an alarm in javascript?

Is it possible to ser a function to start in a given date and hour? How?

I thought about setTimeout, but what开发者_运维知识库's the maximum time I can set?

--update

By the way, it's for a desktop application.

I agree with JCOC611 - if you can make sure that your application does not close, then just get a Date object of when your alarm should go off and do something like this:

window.setTimeout(function() { soundAlarm() }, 
           alarmDate.getTime() - new Date().getTime());

I see no reason for this not to work, but a lot of people exalt a timer based solution where you have a short lived timer that ticks until the set time. It has the advantage that the timer function can also update a clock or a countdown. I like to write this pattern like this:

(function(targetDate) {
    if (targetDate.getTime() <= new Date().getTime()) {
        soundAlarm();
        return;
    }

    // maybe update a time display here?
    window.setTimeout(arguments.callee,1000,targetDate); // tick every second
})(alarmDate);

This is basically a function that when called with a target date to sound an alarm on, re-calls itself every second to check if the time has not elapsed yet.

setTimeout(functionToCall,delayToWait)

As stated in Why does setTimeout() "break" for large millisecond delay values?, it uses a 32 bit int to store the delay so the max value allowed would be 2147483647

Does setTimeout() have a maximum?

http://www.highdots.com/forums/javascript/settimeout-ecma-166425.html

It may surprise you that setTimeout is not covered by an ECMA standard, nor by a W3C standard. There are some holes in the web standards. This is one of them. I'm looking to the WHAT Working Group to fix this. See http://www.whatwg.org/specs/web-apps/current-work/

There doesn't seem to be a problem in setting the timeout value to something that is vastly greater than the MTBF of the browser. All that means is that the timeout may never fire.

http://javascript.crockford.com/ -Douglas Crockford

As others have mentioned, this isn't the way to handle the situation. Use setTimeout to check a date object and then fire the event at the appropriate time. Some code to play with is linked below.

http://www.w3schools.com/js/tryit.asp?filename=tryjs_timing_clock

You should not relay on setTimeout for the actual alarm trigger but for a periodic function tracking the alarm. Use setTimeout to check the stored time for your alarm say every minute. Store that time in DB, file or server.

Is there any server component to this at all? You could use setInterval to call something serverside on a regular basis via ajax, then pull back a date object and once it's finally in the past you could trigger your "alarm"