Synchronize Javascript Timer

Question

I am working on an app that has a javascript interval timer. I would like the timer to run on a server then I would like to grab that time on multiple devices on click.

Ex: Countdown Timer to be displayed on a large screen in a gym (this is coming from the server). I would like users on mobile devices to be able to capture time and record it in real-time.

If the timer on the big screen said 10:35 when I push the button on my mobile device I want it to grab 10:35 and put it into an input field.

I have the timer code figured out. I just don't know how to get the time that is displayed on the server to the other devices.

I know that this is a very general question. I am just wondering if it is possible, and if someone can point me in the right direction.

Thanks!!!

What server side language are you using? – William Oct 23 '13 at 01:20 — William, Oct 23 '13 at 01:20

score 2 · Answer 1 · answered Oct 23 '13 at 01:33

2

If you are using javascript/using node.js...you can use websockets to synchronize your timers in real time.

here is a link to a good tutorial :-) http://www.youtube.com/watch?v=pNKNYLv2BpQ

answered Oct 23 '13 at 01:33

StaleMartyr

778
5
18

score 0 · Answer 2 · edited May 23 '17 at 10:31

Hmmm. This is a particularly difficult problem given the intricacies of keeping time in sync across multiple devices.

Here's the architecture I'd suggest:

The server serves an HTML document to the clients that contains three timestamps: the start time, the end time, and the current server time. This could conceivably be fetched over AJAX.
From the current server time, the client can calculate its current skew and display a countdown timer matching the server ("big board") using client-side Javascript.
A button could then grab the value of a timer and populate the input field.

Here's a pretty similar question.

Synchronize Javascript Timer

2 Answers2