Count down timer in PHP

[Anon]

I'm trying to implement a simple count down timer in PHP for an alarm feature. But I am stumped.

I have a javascript that will do this, but as soon as you leave the page, of course, you lose your timer.

Seems to me, if a person had a similar PHP function, and called it on every page, and also passed around the count value as a session value, this could work. The user could visit any page on your site, and the timer would still know when to trigger.

Any suggestions here? This may simply not be possible in PHP, I don't know.

Thanks in advance.

[Anon]

If the time to count down to is something set by the site vistor, then the best place to store it would be a session variable.

The server would then take that, and on each page where the countdown Javascript is used, write it directly into the Javascript code. The Javascript code then knows when it's supposed to count down to, and it can get the current time from the browser.

If the time to count down to comes from the site itself, then nothing needs to be stashed on the client. Both the time to count down to and the current time would be written into the Javascript code (you don't use the client's local time in this case).