Book Image

WordPress Plugin Development Cookbook - Second Edition

By : Yannick Lefebvre
Book Image

WordPress Plugin Development Cookbook - Second Edition

By: Yannick Lefebvre

Overview of this book

WordPress is a popular, powerful, and open Content Management System. Learning how to extend its capabilities allows you to unleash its full potential, whether you're an administrator trying to find the right extension, a developer with a great idea to enhance the platform for the community, or a website developer working to fulfill a client's needs. This book shows readers how to navigate WordPress' vast set of API functions to create high-quality plugins with easy-to-configure administration interfaces. With new recipes and materials updated for the latest versions of WordPress 4.x, this second edition teaches you how to create plugins of varying complexity ranging from a few lines of code to complex extensions that provide intricate new capabilities. You'll start by using the basic mechanisms provided in WordPress to create plugins and execute custom user code. You will then see how to design administration panels, enhance the post editor with custom fields, store custom data, and modify site behavior based on the value of custom fields. You'll safely incorporate dynamic elements on web pages using scripting languages, and build new widgets that users will be able to add to WordPress sidebars and widget areas. By the end of this book, you will be able to create WordPress plugins to perform any task you can imagine.
Table of Contents (20 chapters)
Title Page
About the Author
About the Reviewers
Customer Feedback

Inserting link statistics tracking code in page body using plugin filters

After creating two filter functions that append text to the existing content, this recipe shows you how to modify the page content before it is displayed on the screen. More specifically, the following plugin will expand on the Google Analytics header plugin created earlier and add a JavaScript function to all the links that are included in posts and pages to track when they are clicked by visitors.

Getting ready

You should have already followed the Adding output content to page headers using plugin actions recipe to have a starting point for this recipe and the resulting plugin should be active in your development site. Alternatively, you can download the resulting code (Chapter 2/ch2-page-header-output/ch2-page-header-output.php) for that recipe from the Packt Publishing website (

How to do it...

  1. Navigate to the ch2-page-header-output folder in the WordPress plugin directory of your...