in _dist/alertify/alertify.js [1472:1484]
function findTabbable(instance, last){
var tabbables = [].slice.call(instance.elements.dialog.querySelectorAll(defaults.tabbable));
if(last){
tabbables.reverse();
}
for(var x=0;x<tabbables.length;x+=1){
var tabbable = tabbables[x];
//check if visible
if(!!(tabbable.offsetParent || tabbable.offsetWidth || tabbable.offsetHeight || tabbable.getClientRects().length)){
return tabbable;
}
}
}