$.browser is undefined

Following the update of WordPress perhaps a feature in one of the plugins has stopped.

Reviewing the page errors with the browser inspector shows the error

$.browser is undefined

I have also encountered the $.browser is undefined error when I took over a website and updated the jQuery references as a part of my initial actions.

With the introduction of jQuery version 1.9 jQuery browser was no longer supported.

To our rescue is a set of scripts called jquery-migrate. The aim of which is to add back in those missing functions. Allowing more time for the changes to jQuery to be incorporated.

To add migration support add

<script src=”http://code.jquery.com/jquery-migrate-1.0.0.js”></script>

to the web page. Take care in its position on the page to get the sequencing right.

$.browser was used to determine which browser was in use, visiting the web page.


jQuery Core 1.9 Upgrade Guide – jQuery.browser() removed

Github jQuery Migrate