serverSync with callback using synchronous XMLHttpRequest fails

[samgavinio]

The suggested serverSync implementation with synchronous XHR (taken from http://keith-wood.name/countdownRef.html)

$(selector).countdown({ 
    until:liftoffTime, serverSync: serverTime
}); 

function serverTime() { 
    var time = null; 
    $.ajax({url: 'http://myserver.com/serverTime.php', 
        async: false, dataType: 'text', 
        success: function(text) { 
            time = new Date(text); 
        }, error: function(http, message, exc) { 
            time = new Date(); 
    }}); 
    return time; 
}

would soon begin failing across all browsers due to the deprecation of synchronous XMLHttpRequests due to its negative effect on user experience. Please see: https://groups.google.com/a/chromium.org/forum/#!topic/chromium-extensions/WH1wOAxJQiM

At the moment there is no other way to use serverSync except for providing a callback that returns the server time using a synchronous XMLHttpRequest

[adis-me]

+1 This could be a showstopper soon.. Without async: false the serviceSync: serverTime is not working.

[tentonaxe]

You could of course simply defer the initialization of the plugin.

function startCountdown(serverTime) {
    $(selector).countdown({ 
        until:liftoffTime, serverSync: serverTime
    });
}

$.ajax({url: 'http://myserver.com/serverTime.php', 
    dataType: 'text', 
    success: function(text) { 
        startCountdown(new Date(text)); 
    }, 
    error: function(http, message, exc) { 
        startCountdown(new Date()); 
    }
}); 

[warrenkc]

@tentonaxe Have you had success with the serverSync? I have not gotten it to work. It seems like no matter what I do the countdowntimer is affected by a local system clock, and not using the server time.

[tentonaxe]

I never used serverSync, I just started the countdown after i retrieved the UTC datetime value from an ajax request. You can't stop the local system clock from impacting the countdown other than by calculating the difference between the two and then adjusting, but then if the user changes their clock after that point in time it'll be off again.