$(document).ready(function () {
    // if user clicked on button, the overlay layer or the dialogbox, close the dialog	
    $('a.btn-ok, #dialog-overlay, #dialog-box').click(function () {
        $('#dialog-overlay, #dialog-box').hide();
        return false;
    });

    // if user resize the window, call the same function again
    // to make sure the overlay fills the screen and dialogbox aligned to center	
    $(window).resize(function () {

        //only do it if the dialog box is not hidden
        if (!$('#dialog-box').is(':hidden')) popup();
    });
});

//Popup dialog
function popup(message) {
    // get the screen height and width  
    var maskHeight = $(document).height();
    var maskWidth = $(window).width();

    // calculate the values for center alignment
    var dialogTop = (maskHeight / 3) - ($('#dialog-box').height());
    var dialogLeft = (maskWidth / 2) - ($('#dialog-box').width() / 2);

    // assign values to the overlay and dialog box
    $('#dialog-overlay').css({ height: maskHeight, width: maskWidth }).show();
    $('#dialog-box').css({ top: dialogTop, left: dialogLeft }).show();

    // display the message
    $('#dialog-message').html(message);
}