I found an error on Google Chrome, since v58.0 there came a new info handler...
[Violation] 'click' handler took 1375ms
This message is not an error (got it via setting the error level to verbose) should definitely not lead to a cancelling of the script, why I read a lot at the net for the last hour. In first instance I thought it could be brought together with the new policy of ssl forms, but I could not verify this thesis at a correct ssl encrypted (Let's Encrypt) site.
Finally I found out, this should be caused by an inappropriate library or script - but I still have no idea how it could be solved without rewriting the jquery script itself. I tried the created button at a list and the form itself - at both the click does not get to an end IF the alert box is set to on.
The html code of the button is at both types:
<div class="btn-wrapper" id="toolbar-delete">
<button class="btn btn-small" onclick="if(!confirm('Sollen die ausgewählten Einträge wirklich gelöscht werden?')){return false;}" href="#"><i class="icon-delete"></i> </button></div>
Just an idea, could it be solved if we move the onclick directly to the href attribute?
Regards, Pierre.