I often find myself being asked to change a wordpress.org or 3rd party purchased plugin. Editing the plugin directly is generally not a good idea, as any changes made will be lost the next time the plugin updates. And if you choose not to update the plugin and a security vulnerability is discovered at a later date, you may wind up with a comprimised site.

One of the most common changes is to modify text that is displayed publicly on the front end. One of the ways you can accomplish this is with the gettext filter. If the plugin has been properly setup for translations & internationalization, you can easily override this text either by adding some code to your theme’s functions file, or (preferably) by creating a new plugin with those customizations.

An example from the WordPress codex itself:

And a real world example from a recent project:

If you upgraded to WordPress 4.5 and suddenly things relying on Javascript are broken on your page, check Chrome dev tools. You may see an uncaught error like this:

Uncaught Error: Syntax error, unrecognized expression: a[href*=#]:not([href=#])

The fix is pretty straight forward. There is a theme or plugin that uses that code. It needs to be replaced with a[href*="#"]:not([href="#"])

The reason for the problem is that WordPress now uses a newer version of jQuery which is less tolerant of incorrectly written code. Which in this case means that the # signs required parenthesis around them.

I cloned a WordPress site, and the new site was throwing a database error page. I repaired all of the tables, I verified that the MySQL credentials were correct, but nothing worked. I finally looked at the wp_options table to see if anything looked wrong. Low and behold, the siteurl was blank. Adding the value back in fixed it.