5 practical uses for the functions.php file in WordPress

There are only two files you need to use when creating a WordPress theme: the index.php file (which serves as the main template file for the website) and style. css file, which is the main style file for your website. There is a third file called functions.php which is not actually required but still plays an important role in the theme.

In this tutorial, our focus will be on understanding what the functions.php file is, some of its common uses, and when you should use it instead of creating a plugin. let's start.

functions.php What is the file?

The

functions.php file in WordPress is used to add new functions or features to your WordPress website. You can write PHP code in this file. This code can define your own custom function or call an existing WordPress function. We’ll look at how to add new functionality to your WordPress website via the functions.php file in the next section.

It is entirely possible to have multiple themes for a WordPress installation. Each theme has its own functions.php file. However, when someone loads your site, only the code in the active theme's functions.php file will actually run.

You need to find the functions.php file before you can edit it. You can find it in the /wp-content/themes/theme-name/ directory. Here, Theme Name is the name of any theme you have installed and activated.

Any child theme you install on your site can also have its own functions.php file. Unlike other themes, a child theme's functions.php file does not overwrite the parent theme's functions.php file. It actually adds functionality provided by the parent theme.

functions.php File usage

You can perform many operations using the functions.php file. We'll look at some of them here.

Queue Scripts and Styles

You may want to include additional scripts and styles in your website to load on the front end. The best way to achieve this is with the help of the wp_enqueue_scripts hook. Contrary to its name, this hook is useful for enqueuing scripts and styles. Here's an example of using it in a functions.php file.

function monty_scripts_styles() {
    wp_enqueue_style( 'my-style', get_template_directory_uri() . '/css/custom-style.css', array(), '1.2.0', 'all' );
    wp_enqueue_script( 'my-script', get_template_directory_uri() . '/js/custom-script.js', array( 'jquery' ), '1.5.6', true );
}

add_action( 'wp_enqueue_scripts', 'monty_scripts_styles' );

Using the wp_enqueue_scripts hook to add styles and scripts ensures that files are not loaded multiple times etc. thus improving performance. You can learn more by reading this tutorial on how to load CSS into WordPress the right way.

The

wp_enqueue_style() and wp_enqueue_script() functions accept multiple arguments to specify sources, versions, dependencies, etc.

Create custom shortcode

WordPress shortcodes help people add dynamic or static content to their website without writing complex code. Think something like a list of your latest posts, a few images from your gallery, the current date, or a simple hello.

You can add custom shortcodes by writing some code in the functions.php file.

function monty_greeting_shortcode() {
    $current_user = wp_get_current_user();
    
    if($current_user) {
        $name = $current_user->display_name;
    } else {
        $name = 'Guest';
    }
    
    $greeting = 'Hello, '.$name.'!';
    
    return $greeting;
}

add_shortcode( 'greet_readers', 'monty_greeting_shortcode' );

This is a very simple example, you can use the greet_readers shortcode anywhere in the frontend to add a greeting for logged in users Hello, Display Name! and Hello , Guest! For others.

Now try writing your own shortcode to return the content you want to display.

Delete WordPress version number

You may be interested in checking your website’s WordPress version for a number of reasons.

However, this information should not be publicly visible. WordPress has added a generator meta tag that publicly displays the version of WordPress currently installed on your site in the HTML source code. You can simply add the following lines to your functions.php file to remove the generator tag.

add_action( 'wp_head', 'wp_generator');

If you also want to remove information from other places (such as RSS feeds), consider using the following lines.

add_filter('the_generator', '__return_empty_string');

The built-in __return_empty_string() function will return an empty string and prevent your version information from being displayed on the frontend.

Disable WordPress Admin Toolbar

By default, WordPress adds an admin toolbar at the top of the frontend for all logged in users. You can add the following lines in your functions.php file to disable it for everyone immediately.

add_filter( 'show_admin_bar', '__return_false' );

Keep in mind that the WordPress admin toolbar cannot be disabled on the backend.

禁用 WordPress 自动更新

虽然通常不建议您在网站上禁用 WordPress 自动更新，但您可能出于多种原因想要这样做，例如防止意外故障。您应该阅读本教程以了解有关 WordPress 自动更新的更多信息。

如果您确定要禁用 WordPress 自动更新，请将以下行添加到您的 functions.php 文件中。

add_filter('auto_update_core', '__return_false');
add_filter('auto_update_theme', '__return_false');
add_filter('auto_update_plugin', '__return_false');

这三行将分别禁用核心更新、主题更新和插件更新。

最终想法

在本教程中，我们学习了很多有关 functions.php 文件的知识。我们现在知道这个文件是什么、它位于哪里，以及如何使用它向我们的网站添加新功能。还可以使用插件向您的网站添加功能。那么最好的方法是什么？

如果您要添加的功能是特定于主题的，或者您只想添加一点点新功能，则应该考虑使用 functions.php 文件。为每件小事创建和安装新插件都会损害您网站的性能。

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