CODE EXAMPLE FOR JAVASCRIPT

make popup js

function popup(url, width, height) {
    var left = (screen.width/2)-(width/2);
    var top = (screen.height/2)-(height/2);
    return window.open(url, '', 'toolbar=no, location=no, directories=no, status=no, menubar=no, scrollbars=no, resizable=no, copyhistory=no, width='+width+', height='+height+', top='+top+', left='+left);
}