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Created: January 24th 2024
Last updated: January 30th 2024
Categories: Common Web Development,  IT Development,  Php,  Wordpress
Author: Tim Fürer

WordPress: CSS/JavaScript Changes not Showing/Loading

Tags:  cache,  CSS,  functions.php,  Javascript,  PHP,  wordpress
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Here's a bit of wisdom from the trenches: dealing with browser caches can feel like playing a never-ending game of hide and seek with your updates. Ever made a slick update to your site, only to clients complain they can't see it? That's the browser cache, playing tricks on you, ignoring and refusing to fetch your recent updates. But fear not, I've got a trick up my sleeve to outsmart it.

Caching: The Good and The Bad

Let's set the scene: you've pushed a crucial update - maybe fixed a bug or adjusted a layout, made changes to some JavaScript or CSS file(s). You're proud, you're relieved, you're... confused. Because now your inbox is filling up with emails asking why nothing's changed. Well, their browsers are still partying with your old scripts and styles, blissfully unaware of your latest masterpiece.

Caching resources in the browser offers notable benefits but, as shown, also presents challenges. On the upside, it enhances performance through faster page loads, reduces server load, and saves bandwidth by storing files locally. This leads to a smoother user experience and improved website efficiency. However, the major challenge lies in the risk of outdated content. Cached files don't reflect recent updates and thus returning users can encounter discrepancies and errors.

An EAsy Fix

Here's where we get clever. WordPress lets us add a little twist to the way we enqueue scripts and styles, a twist that gently nudges browsers to take notice of our updates.

Let’s dive into some code that makes this magic happen:

function enqueue_resources() {
    // Example: Enqueue Style
    $style_path = get_stylesheet_directory() . '/my-style.css';
    wp_enqueue_style(
        'my-style',
        get_stylesheet_directory_uri() . '/my-style.css',
        [],
        file_exists($style_path) ? md5_file($style_path) : false,
    );

    // Example: Enqueue Script
    $script_path = get_template_directory() . '/my-script.js';
    wp_enqueue_script(
        'my-script',
        get_template_directory_uri() . '/my-script.js',
        [],
        file_exists($script_path) ? md5_file($script_path) : false,
        true,
    );
}
add_action('wp_enqueue_scripts', 'enqueue_resources');

This snippet uses md5_file() to create a unique hash for your file. When the file changes, so does the hash, signaling to browsers that it’s time to clear out the old and fetch the new version.

 

The Benefits

  • Smoother Updating: Eliminates the "I can’t see the update" issue. Have your adjustments be reflected on your website immediately. No more "CTRL + F5" or "SHIFT + CTRL + R".
  • Reduced Frustration: Both for you and your clients. May be life-prolonging (disclaimer: I'm not an actual health expert).

Limitations

  • Imports and External Content: Modern CSS and JavaScript allows us to import external resources via import statements. Unfortunately, those external files being modified won't prompt our main files (the ones we enqueue) to update their hashes in any way.

Wrapping Up

In conclusion, browser caching of CSS and JavaScript files is a double-edged sword. It significantly improves website performance and user experience but requires careful management to prevent issues like the browser loading outdated resources. By using techniques like the MD5 hashing method presented in this article, you can more effectively harness the advantages of caching while mitigating its risks, ensuring your site remains both fast and up-to-date.