Javascript Cookie Timeout With Countdown Timer

Question

I want to set a cookie with javascript. Easy enough. Lets say I set it for 15 minutes.

How would I make a count down timer show to show when the cookie expires? And even if they left the page I would want it to keep counting and when they come back to the page it would still have been counting down.

Sorry for the poor explanation. But I'm fairly sure its possile.

Thanks

Answer 1

Store the time stamp of now + 15 minutes within a cookie if there is no cookie. Write a simple script that checks the difference between now and the timestamp every second.

Edit: sample code

// 200 seconds countdown
var countdown = 200; 

//current timestamp
var now   = Date.parse(new Date());

//ready should be stored in your cookie
var ready = Date.parse(new Date (now + countdown  * 1000)); // * 1000 to get ms


//every 1000 ms
setInterval(function()
{
    var sec = ( ready - Date.parse(new Date()) )/1000;
    document.title = sec + " seconds left";

},1000);