Action Hook is an "insert point" in WordPress execution process, allowing developers to add custom features without modifying core code. Common usage scenarios include loading resources, performing operations, modifying jump logic, inserting statistical code, etc. Common hooks include init, wp_enqueue_scripts, admin_init, wp_footer and save_post. To add an Action Hook, you need to use the add_action() function, the format is: add_action('hook name', 'callback function name', priority, number of parameters). When not specified, the default priority is 10 and the number of parameters is 1. When choosing the appropriate hook, you need to pay attention to its operating environment (foreground or background). For example, wp_enqueue_scripts is used for front-end resources, admin_enqueue_scripts is used for background resources, and wp_login is used for user login operations. If necessary, remove_action() is used to remove the default hook to cancel the original behavior, but you must know the hook name and corresponding function name to successfully remove it. Mastering the use of Action Hooks can improve WordPress development efficiency and enhance the clarity of code structure.

In WordPress development, Action Hooks are one of the core mechanisms for building plug-ins and theme functions. By using action hooks, you can insert custom functions into specific execution points without modifying the core code. Understanding and using them correctly can make your development work more efficient and structured.

What is an Action Hook?

Action Hook is the "insert point" in the WordPress execution process. You can mount a custom function to an action hook, and your function will be automatically called when WordPress runs to that point.

For example, after the page is loaded, you want to add a script, and you can bind the function to wp_footer hook. WordPress triggers it when it outputs footer content.

Common Action Hook usage scenarios

• Loading CSS/JS resources in the foreground or background
• Perform certain actions after the article is published
• Modify the jump logic after login
• Insert statistics codes, advertising spaces, etc.

Some commonly used action hooks include:

• init
• wp_enqueue_scripts
• admin_init
• wp_footer
• save_post

How to add an Action Hook

To add a custom function to an action hook, the add_action() function is mainly used. Its basic format is as follows:

 add_action('hook name', 'callback function name', priority, number of parameters);

For example, if you want to output a piece of HTML content in the website footer:

 function my_custom_footer_content() {
    echo &#39;<p>This is a custom footer information</p>&#39;;
}
add_action( &#39;wp_footer&#39;, &#39;my_custom_footer_content&#39; );

There is no priority and number of parameters specified here, the default is 10 and 1, which is sufficient in most cases. But if you want your function to be executed earlier than others, you can set a lower priority number (such as 5), and vice versa (such as 20).

How to choose the right hook?

Choosing the right hook is the key. Some hooks only run in the foreground, while others only take effect in the background. for example:

• If you want to load front-end resources, you should use wp_enqueue_scripts
• Use admin_enqueue_scripts for background resources
• Want to do something after the user logs in? Try wp_login

There is a complete list of Action Hooks in the official document. It is recommended to check it when you encounter uncertainty.

Additionally, themes and plugins may also provide their own hooks. For example, WooCommerce has many exclusive action hooks for inserting content on product pages. At this time, you have to look at the corresponding plug-in documentation.

Don't forget to remove the default hook

Sometimes you not only want to add things, but also want to cancel the original behavior. At this time, you can use remove_action() to remove the function on a certain hook.

For example, some topics will display extra content on the homepage, which may be implemented through the_content or some custom hook. If you want to turn it off:

 remove_action( 'theme_custom_hook', 'theme_function_name' );

It should be noted that you must know the removed hook name and the corresponding function name to successfully delete it. If you don't know this information, you may have to search the template file or functions.php of the topic.

Basically that's it. Mastering the use of action hooks will make you more comfortable in WordPress themes or plug-in development. Although it looks simple, there are still many details to pay attention to when using, especially the choice of priority and hooks.

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