tl;dr WordPress 4.2.4 RC1 is available (download) for testing and fixes an issue with inline scripts.

A change in WordPress 4.2.3 had the unintentional side effect of breaking some inline scripts when the CDATA blockBlock Block is the abstract term used to describe units of markup that, composed together, form the content or layout of a webpage using the WordPress editor. The idea combines concepts of what in the past may have achieved with shortcodes, custom HTML, and embed discovery into a single consistent API and user experience. is used (see #33106). For example, consider the intended content here:

<script>// <![CDATA[ _my_function('data'); // ]]> </script>

In 4.2.2, this content is left as is and _my_function() fires as expected. In 4.2.3, the content is manipulated as such:

<script>// <![CDATA[ _my_function('data'); // ]]></script>

This results in the script being commented out by the // and it will not fire. A workaround for this is to use /* for commenting.

<script> /* <![CDATA[ */ _my_function('data'); /* ]]> */ </script>

However, this workaround should not be necessary. As a result, we intend on releasing WordPress 4.2.4 to fix this issue.

Additionally, WordPress 4.2.3 caused issues when using shortcodes within angle brackets (see #33116). For example, this shortcodeShortcode A shortcode is a placeholder used within a WordPress post, page, or widget to insert a form or function generated by a plugin in a specific location on your site. usage worked in 4.2.2 but did not work in 4.2.3:

<[shortcode]>

While we do not recommend this use of shortcodes and strongly encourage pluginPlugin A plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites. WordPress plugins are written in the PHP programming language and integrate seamlessly with WordPress. These can be free in the WordPress.org Plugin Directory https://wordpress.org/plugins/ or can be cost-based plugin from a third-party developers to move away from this use of shortcodes, the breakage was unintentional and we have restored the behavior in WordPress 4.2.4 RC1.

Please download and test WordPress 4.2.4 RC1 and report any issues to core trac or to this post.