Troubleshooting React CSS Modules: Why .default Class Name Isn't Working

Encountering issues with React CSS modules not applying class names? Learn how to solve the problem with `.default` and style your components effectively.
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Troubleshooting React CSS Modules: Why .default Class Name Isn't Working

When working with React, sometimes we encounter unconventional bugs that can lead to frustration, especially when it comes to styling components. If you've found yourself in a scenario where your CSS class names simply aren't being applied, you're not alone! This post dives into a common issue faced by developers using React CSS modules, specifically related to the class name .default in a button component.

The Problem

You have a React button component that you're trying to style with CSS modules. You've correctly defined your styles in a module file and utilized the class names from this file in your component. However, the classes are not being rendered on the button, as evidenced by inspecting the output in the browser. This has led you to seek help from the community after hours of troubleshooting without success.

Key Points of the Issue:

The CSS classes exist in the source but are not rendered correctly.

The intended styles do not apply, leaving the elements with default styling instead.

Analyzing the Code

Here's a breakdown of the code components involved:

1. The Button Component

Sample implementation:

[[See Video to Reveal this Text or Code Snippet]]

2. CSS Module

[[See Video to Reveal this Text or Code Snippet]]

3. Rendering the Button

[[See Video to Reveal this Text or Code Snippet]]

Upon rendering, the actual output looked like this (notice the button has an empty class):

[[See Video to Reveal this Text or Code Snippet]]

Finding the Solution

After a thorough examination and testing, it became evident that the issue stemmed from the class name .default in your CSS module. Here’s what you might want to note:

Potential Reasons for the Issue

Reserved Keywords: It's possible that .default is a reserved term in some context of React or certain loaders used by Parcel.

Conflicts in Naming: Class names matching common JavaScript keywords can sometimes cause conflicts, resulting in improper rendering.

The Fix

Rename the Class: As a workaround, renaming the .default class to something more specific like .buttonDefault will likely resolve the issue.

Recheck Imports: Ensure that your imports and file paths are correct, and rebuilt your project to clear any cache issues.

Example of the Updated CSS

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Working through issues with styling in React can be challenging, especially when the problems arise from unexpected places like reserved keywords. Fortunately, understanding the underlying cause can lead you to a straightforward solution, such as renaming conflicting class names to avoid ambiguity.

If you find yourself running into similar issues, remember to double-check your class naming conventions and keep updating your knowledge of any restrictions that libraries might impose. Happy coding!