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Preparing for Drupal 11: The Slick Carousel and jQuery 4 Gotcha

· 3 min read
Victor Jimenez
Victor Jimenez
Software Engineer & AI Agent Builder

As the Drupal community gears up for Drupal 11, developers are scanning for breaking changes that could impact their sites. One such change, the upgrade to jQuery 4, introduces a subtle but critical "gotcha" for sites using the popular Slick Carousel module.

The Problem: $.type is No More​

Drupal 11 will ship with jQuery 4, a major update to the ubiquitous JavaScript library. As part of its modernization, jQuery 4 removes several deprecated functions, including jQuery.type(), also known as $.type().

For years, many JavaScript libraries, including the underlying Slick Carousel library, used $.type() for type checking. When a site running an older version of the Slick Carousel module is upgraded to Drupal 11, the browser's JavaScript console will light up with a fatal error: Uncaught TypeError: $.type is not a function. This error halts script execution, and any Slick carousels on the page will fail to initialize, breaking the layout and user experience.

The Solution: Update and Validate​

Fortunately, the fix is straightforward. The maintainers of the Slick Carousel module have already addressed this incompatibility. The solution involves patching the slick.js file to replace the deprecated $.type() calls with the modern, native JavaScript typeof operator.

To ensure your carousels survive the upgrade to Drupal 11, you must update the module to a compatible version (3.0.3+, but always prefer the latest stable release).

Here’s how the code changes, conceptually:

// Example from older slick.js
if ( $.type( something ) === 'object' ) {
  // ... do object things
}

By updating the module, you receive the patched library that works with jQuery 4. You can do this easily with Composer:

composer update drupal/slick --with-dependencies

After updating, be sure to clear Drupal's caches and thoroughly test all pages where carousels are used.

What I Learned​

  • Upstream Dependencies are Your Dependencies: The Slick Carousel module relies on an external JavaScript library. When a Drupal core dependency (jQuery) changes, it can have a cascading effect on contributed modules. This is a critical lesson in dependency management.
  • Proactive Maintenance is Key: Simply keeping your contributed modules up-to-date is the single most effective way to prepare for major Drupal version upgrades. The fix for this issue was available long before Drupal 11's release.
  • Consult the Issue Queue: Before any major upgrade, the Drupal.org issue queue for your key modules is an invaluable resource. A quick search for "Drupal 11" or "jQuery 4" would have highlighted this problem early.

Staying ahead of deprecations and breaking changes is a core part of modern web development. This Slick Carousel issue is a perfect example of a small change in a core dependency causing significant problems if not addressed proactively.

References​