I want to have a confirm box when user tries to close the window.

window.onbeforeunload = function (evt) {
var message = 'Are you sure you want to leave, cause there are some unsaved changes?';
if (typeof evt == 'undefined') {
evt = window.event;

}
if (evt ) {
evt.returnValue = message;
}

        return message;

}

The thing is i want to check a variables value

    var sncro=1;

If its value is not equal to one then this confirmation box should be there..else no need to have a confirmation. I m not able to figure this..Its soo silly but i request anybody can have a look on the code. thnks.