How to create a countdown timer and run a sql query with PHP when it is completed?

Question

I am using the following jQuery script that countdowns the time until the $end and when this happen it displays completed.

However when you change the time on your computer, the countdown is changed. What I had in mind is like those countdowns that Groupon has.

My question is how to change the time source in something that can not be changed, maybe the server's time? And when the timer reaches 0, how can I run a SQL query using PHP?

Am I totally in the wrong way?

Thank you.

<?php $end = 'september 1, 2011 19:24'; ?>

<script type="text/javascript">
$(document).ready(function() {
    $("#time").countdown({
        date: "<?=$end?>",
        onComplete: function( event ){
            $(this).html("<i>Completed</i>");
        },
        leadingZero: true
    });
});
</script>

<p id="time" class="time"></p>

@Dan Grossman can you please take a look on my new question at stackoverflow.com/questions/7101267/… — EnexoOnoma
– EnexoOnoma, Commented Aug 18, 2011 at 1:20
@Nikolai You did not answer what this query is there either. — Dan Grossman
– Dan Grossman, Commented Aug 18, 2011 at 1:23
@Nikolai There is no reason to do that. The fact that the row is finished is known because the date is less than now (or the 'completed date'). A separate column to mark the row as finished would be duplication of data. You can select the 'unfinished' rows by selecting those with future dates. You can select the 'finished' rows by selecting those with old dates. No need to mark anything! — Dan Grossman
– Dan Grossman, Commented Aug 18, 2011 at 1:32

Tejs · Accepted Answer · 2011-08-17 18:23:05Z

1

This may be the worst idea in existance, but perhaps you can simply calculate the time between now and the end date once, find the number of intervals you want, and then call setInterval and manually decrement the value.

AKA:

var initialTime = new Date();
var endTime = /* Your Time when the thing is over */

var intervalId = setInterval(function()
{
    // Every second, decrement the counter by 1 second. 

    // if counter is done, show end and then
    clearInterval(intervalId);
}, 1000);

answered Aug 17, 2011 at 18:23

Tejs

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4 Comments

EnexoOnoma Over a year ago

Should I use a PHP script instead?

Tejs Over a year ago

You can do that entirely in JavaScript.

EnexoOnoma Over a year ago

Do you have any example? What I concern is that when the timer reaches 0 I have to run a sql query...

Dan Grossman Over a year ago

You do not need to run a query when the timer reaches 0. You think you do, but whatever reason you think you need to run that query when the timer hits 0 does not actually need to happen.

JJJ · Accepted Answer · 2011-08-17 19:12:04Z

It's ok to have a JavaScript countdown timer in most situations, but you can't rely on a client-side script not to "speed up" the timer. The user can always cheat the timer by changing the system clock, messing with the JavaScript variables manually, and so on.

Reading between the lines it seems like you want to do something like put a note in the database when a product comes available or an offer expires. If so, you should absolutely do this server-side, especially if the query must be run even if the user navigates away from the page and maybe returns only after the deadline. Maybe re-think the logic completely: instead of making a note in the database at the time the timer runs out, put the expiration time in the database beforehand that marks when the change comes into effect.

Another possibility is when the JavaScript timer hits the mark have the page make a call to the server. The server then checks if the call has been made at the correct time. If so, run the SQL query, but otherwise tell JavaScript that it should keep the timer running. (For example if the server thinks the call was made 10 minutes early, return data to JavaScript saying that it should reset the timer to 10 minutes and then try again.)

Yavor S · Accepted Answer · 2011-08-17 18:22:40Z

0

What you are asking is impossible. You can use setTimeout which will fire after a specific number of milliseconds.

answered Aug 17, 2011 at 18:22

Yavor S

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