An Introduction to WordPress Plugin Development

WordPress plugins offer a powerful way to enhance the functionality of your website. You can extend your site’s features beyond what’s available in the core WordPress platform, without directly editing any code.With thousands of plugins available in the WordPress Plugin Directory, why develop your own? Creating your own plugins lets you add customized functionality to your website, which may not be available in any existing plugins.

How WordPress Plugins Work

In order to develop your own plugin, it’s critical to first understand how the key systems work. Plugins operate primarily using hooks, which are a way for one piece of code to interact with (‘hook into’) another. WordPress has two types of hooks: actions and filters. We’ll discuss these in more detail below, along with two other elements that are commonly used in plugin development.

Actions

A WordPress action refers to a specific activity that is going to happen at a particular time. With actions, you can add or change the functionality of your plugin. The functions that are attached to an action will be executed once that action is triggered.

Filters

WordPress filters are hooks that accept a single variable or a series of variables, and then sends them back after they’ve been modified. In a nutshell, filters let you change the content that is displayed to users. WordPress filters are created using the apply_filters function, and are defined inside of that function. They require the $tag (the filter name) and $value (the filtered value or variable) arguments, with the option of using $var for extra function values.

Shortcodes

Put simply, shortcodes are user-facing bits of code that give users a quick and easy way to create and display custom functionality to their sites’ visitors. Shortcodes can be placed in posts and pages via the editor, in menus and widgets, and so on. Many plugins make use of shortcodes. You can create your own shortcode by using the add_shortcode function. The name of your shortcode will be the first variable, and the second variable will be the output function. The output function consists of three values: attributes, content, and name.

Widgets

Another way to enable plugin functionality through a simple interface is by using WordPress widgets. You can create a widget by extending the WP_Widget class. WordPress uses an object-oriented design approach to widgets, meaning that the functions and values are stored in the single entity of a class.