How to Add Conditional Logic to Your Code Snippets in WordPress

Many WordPress users turn to the 'Code Snippets' plugin to safely add custom PHP, CSS, or JavaScript to their sites without editing theme files. A common challenge is controlling where and when these snippets run. You might want a snippet to execute only for logged-in users, on a specific page, or if a certain plugin is active. This guide explains the core concepts of conditional logic and provides practical solutions to implement it.

Why Conditional Logic is Important

Running code snippets without conditions can lead to conflicts, errors, or unnecessary code loading on pages where it isn't needed, potentially slowing down your site. Conditional logic acts as a set of rules that tells WordPress to execute your code only when specific criteria are met.

Understanding the Current 'Code Snippets' Features

Based on community discussions, the native 'Code Snippets' interface currently offers basic location controls (run snippet in admin, on the frontend, or everywhere). The 'Code Snippets' team has indicated that a more advanced conditional logic feature with a user interface is in development. Until that is released, the primary method for adding conditions is by writing the logic directly into your snippet's code using native WordPress functions.

Common Conditional Scenarios and Solutions

1. Run a Snippet on Specific Pages

To check if you are on a particular page or a page containing a specific slug, you can use WordPress conditional tags inside your function.

add_action( 'wp_head', function () {
    // Check if it's the front page
    if ( is_front_page() ) {
        // Your code for the homepage here
    }

    // Check for a page with a specific slug
    $page = get_queried_object();
    if ( $page && is_page() && str_contains( $page->post_name, 'your-slug' ) ) {
        // Your code for pages with 'your-slug' here
    }
} );

2. Run a Snippet Based on User Status or Role

A critical best practice is to check for user status inside your action or filter hook. Checking too early, when the snippet is first loaded, will not work correctly because user data is not yet available.

add_action( 'wp_head', function () {
    // Get the current user
    $user = wp_get_current_user();

    // Check if the user is logged in
    if ( ! is_user_logged_in() ) {
        // Code for guests (not logged in)
        return;
    }

    // Check if the user has a specific role
    if ( in_array( 'customer', (array) $user->roles ) ) {
        // Code for users with the 'customer' role
        ?>
        <style>
            .some-element { display: none; }
        </style>
        <?php
    }
} );

3. Check if a Plugin is Active

You can run a snippet only if a specific plugin is active by checking if a class or function from that plugin exists.

// Check if WooCommerce is active before running the code
if ( class_exists( 'WooCommerce' ) ) {
    add_action( 'init', function () {
        // Your WooCommerce-specific code here
    } );
}

4. Run a Snippet on a Specific Template

WordPress provides numerous template tags to identify the type of page being viewed.

add_action( 'template_redirect', function () {
    if ( is_home() || is_single() || is_page() || is_category() || is_tag() ) {
        // Your code for these template types
        header( 'Cache-Control: max-age=300' );
    }
} );

5. Using Constants for Cross-Snippet Conditions

If you need to set a value in one snippet and read it in another, use a constant instead of a variable, as variables do not persist between snippets. Define the constant in a snippet with a high priority (a low number like 1).

// Snippet 1: Define the constant (Priority: 1)
const SITE_ID = 1;

// Snippet 2: Use the constant
if ( SITE_ID === 1 ) {
    // Do something
} else {
    // Do something else
}

Troubleshooting Common Issues

• Condition Not Working: The most common cause is executing a conditional check (like is_bbpress() or user role checks) before WordPress has loaded the necessary data. Always place your conditional logic inside an action hook like wp_head, template_redirect, or init to ensure the functions are available.
• Site Crashes (White Screen): A syntax error in your PHP code, such as a missing semicolon or bracket, will cause a fatal error. Double-check your code for typos. If your site crashes, you can recover by renaming the code-snippets plugin folder via FTP/SFTP, which will deactivate it and all snippets.
• Variable Not Retaining Value: Variables defined in one snippet are not accessible in another. Use a constant as shown above to share values.

By mastering these conditional techniques, you can ensure your code snippets run precisely where they are needed, making your site more efficient and stable.