Why is the $.widget Not a Function Error Occurring in Magento 2?

Check Module Dependencies

Before diving into the code, it's essential to ensure that the necessary jQuery UI modules are being properly loaded.

In the provided code example, the usage of jquery/ui suggests that the jQuery UI widget factory should be available.

However, it's worth verifying that all required jQuery UI modules are being included and loaded correctly.

Verify jQuery UI Versions

In some cases, compatibility issues between jQuery and jQuery UI versions can lead to the "$.widget is not a function" error.

Ensure that the versions of jQuery and jQuery UI being utilized are compatible with each other.

Upgrading or downgrading either library to a compatible version can often resolve this issue.

Check for jQuery UI Namespace Conflicts

Namespace conflicts or overrides within JavaScript modules can also cause $.widget to become inaccessible.

Check for any potential conflicts with other JavaScript libraries or modules that may be impacting the jQuery UI widget factory's availability.

Solution: Properly Load jQuery UI Modules

In the provided code example, ensure that jquery-ui-modules/core and jquery-ui-modules/widget are correctly defined and loaded as dependencies.

Double-check that the correct paths and module names are being used for jQuery UI modules to prevent any loading issues.

Resolving the "Uncaught TypeError: $.widget is not a function" error in Magento 2 often involves verifying module dependencies, ensuring jQuery UI compatibility, and detecting namespace conflicts. By carefully examining these aspects and making necessary adjustments to the code and module loading, you can address this error and restore the functionality of $.widget in your Magento 2 project.