Countdown timer that counts down the execution of php script

Without knowing what your script does, there is no way to know ahead of time how long it will take to run. Even if we did know what it does, to know the precise time it will take to run really is not possible. If this is all within the same session you could put "% complete markers" at certain main points in your script. I do this in a few places. It makes a nice progress bar and I also show the total elapsed run time as well. If something like this is what you want then read on...

(this is using a jQuery UI progress bar)

If your script is a loop and each iteration is basically doing the same thing then the growth of the progress bar will be pretty fluid. If this isn't the case, and your script does many things very fast, then a few things very slow, then you bar will be like pretty much all Windows progress bars :) It could get to a certain point very quickly then hang there for a while.

Not at my PC so I'm sure there are typos below but you should be able to get the point. Hope this helps...

Something like this would be in your long running script...

$_SESSION["time_start"] = microtime(true);    
$_SESSION["percentComplete"] = 0;
... some of your php script ...
$_SESSION["percentComplete"] = 10;
... some of your php script ...
$_SESSION["percentComplete"] = 20;
... some of your php script ...
$_SESSION["percentComplete"] = 30;
... etc ...
$_SESSION["percentComplete"] = 100;
die();
?> //end of your php script

but if your long running script is a loop it would be more like this...

$loopCnt = 0;
//your php loop
{
    $loopCnt = $loopCnt+1;
    //...the meat of your script...
    $_SESSION["percentComplete"] = round(($loopCnt/$totalRecordCount)*100);
}
$_SESSION["percentComplete"] = 100;
die();
?> //end of your php script

Then on the page the user interacts with an ajax ping could be setup to check the value of $_SESSION["percentComplete"] every couple seconds or so and make the progress bar grow based off the result. Something like...

function checkScriptProgress()
{
    $.ajax({
        url: "checkScriptProgress.php",
        type: 'get',
        cache: false,
        success: function( data, textStatus, jqXHR) {
            //(1) MOVE THE PROGRESS BAR
            //if you are using a jQuery UI progress bar then you could do something like...
            //jQuery("#yourProgressBar").progressbar( "option", "value", data.progress );
            //if you are using HTML5 progress bars it would look like...
            //var pBar = document.getElementById("yourProgressBar");
            //pBar.value = data.progress;

            //(2) UPDATE ELAPSED TIME
            //if you want to display the total run time back to the user then use: data.totalRunTime

            //(3) If report is not finished then ping to check status again
            if (data.progress < 100) setTimeout("checkScriptProgress();", 1000); //check progress every 1 second so the progress bar movement is fluid
        })
    });
}

Then the checkScriptProgress.php file would look something like...

<?php
    header('Content-Type: application/json');
    $time_end = microtime(true);
    $time = $time_end - $_SESSION["time_start"];
    echo '{"progress":'.$_SESSION["percentComplete"].',"totalRunTime":'.$time.'}';
    die();
?>