Mastering Tailwind CSS: Overcome Styling Conflicts With Tailwind Merge and clsx

People have been emailing and asking me to write something on some soft topics for beginners, as I write mostly for mid-level or seniors. So, here is a new article for beginners, especially for UI developers.

Today, let's explore the common challenges developers face when working with Tailwind CSS and how to overcome them using the powerful combination of Tailwind Merge and clsx.

What's the Problem?

When using Tailwind CSS, you often want to pass custom class names to your components, just like you would with a native HTML element, which allows you to style your components dynamically and override the default styles. However, this can lead to conflicts when the custom class names clash with the base Tailwind classes.

The problem with Tailwind is these conflicts are not predictable. You don't know the outcome, really. It doesn't matter if you put this at the front of the class list or at the end; in both cases, when you have a conflict, you don't really get the result that you expect.

The default behavior of Tailwind doesn't always align with our intuition, where we expect the last class to take precedence in case of a conflict.

Introducing Tailwind Merge

The finest solution to this tricky problem is a utility function called Tailwind Merge. This function intelligently merges conflicting Tailwind classes. It makes sure that the last class wins, which aligns with our expectations.

import { twMerge } from 'tailwind-merge';

const containerClasses = twMerge(  'bg-blue-500 text-white px-4 py-2 rounded',  'bg-red-500'
);

In the example above, the twMerge function takes the base Tailwind classes and the custom class name as arguments and returns the merged result. This way, the bg-re-500 class will override the bg-blue-500 class, as expected.

Handling Conditional Classes

Another common scenario is when you need to apply different classes based on a condition, such as a component's state. Tailwind Merge makes this easy to manage as well:

const buttonClasses = twMerge(  'bg-blue-500 text-white px-4 py-2 rounded',  'bg-green-500',  isLoading && 'bg-gray-500'
);

In this case, if the isLoading variable is true, the bg-gray-500 class will be added to the final class string.

Introducing clsx

While Tailwind Merge solves the problem of conflicting classes, some developers prefer to use an object-based syntax for conditional classes. This is where the clsx library comes in handy.

import clsx from 'clsx';

const buttonClasses = twMerge(  clsx({    'bg-blue-500 cursor-not-allowed': !loading,    'bg-gray-500 cursor-pointer': loading,  }),  'text-white px-4 py-2 rounded'
);

By using clsx, you can now define your conditional classes in an object-based format, which some developers find more intuitive.

Combining the Powers of Tailwind Merge and clsx

To get the best of both worlds, you can combine Tailwind Merge and clsx using a custom utility function:

import { twMerge } from 'tailwind-merge';
import clsx from 'clsx';

export const cn = (...inputs: ClassValue[]) => {  return twMerge(clsx(inputs));
};

This cn (short for "class names") function first passes the input classes through clsx, which handles the object-based conditional classes, and then passes the result to Tailwind Merge to resolve any conflicts.

Now, you can use this cn function in your components with both syntaxes:

const buttonClasses = cn(  {    'bg-blue-500': !pending,    'bg-gray-500': pending,  },  'text-white px-4 py-2 rounded'
);

Or:

const buttonClasses = cn( 'text-white px-4 py-2 rounded', pending ? 'bg-blue-500' : 'bg-gray-500' );

This approach allows you to leverage the strengths of both Tailwind Merge and clsx together, providing a flexible and intuitive way to manage your component styles.

Conclusion

In conclusion, understanding and mastering the use of Tailwind Merge and clsx can greatly improve your experience when working with Tailwind CSS. By combining these tools, you can effectively manage class conflicts and conditional styles, and create reusable, well-structured components.