$('*[data-toggle="dropdown"]').click(function (e) {

    // X postion get
    var viewPortHeight = $(window).height();
    var getCurrentPostion = e.clientY;

    // set automatic position in viewport
    console.log(viewPortHeight, getCurrentPostion);

    // if ((viewPortHeight - selfPostion) < droplistHeight) {
    if ((viewPortHeight / 2) < getCurrentPostion) {
        console.log('if');
        $(this).parent().removeClass('dropdown');
        $(this).parent().addClass('dropup');
    } else {
        console.log('else');
        $(this).parent().removeClass('dropup');
        $(this).parent().addClass('dropdown');
    }

});