Understanding the Differences Between clsx, classnames, and twMerge in React and Tailwind CSS

When working with React and Tailwind CSS, managing dynamic classes can become complex, especially when needing to conditionally combine multiple classes. Libraries like clsx, classnames, and twMerge can be incredibly useful in this context.

Here’s a comparison of these libraries.

clsx

• NPM: https://www.npmjs.com/package/clsx
• Function: clsx is a small utility for conditionally constructing class strings.
• Usage: Combines conditional classes in a simple and readable way.
• Advantages: Small package size. Supports objects, arrays, and strings. Automatically removes false or null classes.

import clsx from 'clsx';

const buttonClass = clsx('btn', {
  'btn-primary': isPrimary,
  'btn-secondary': isSecondary,
});        

classnames

• NPM: https://www.npmjs.com/package/classnames
• Function: classnames is a utility similar to clsx, used for conditionally combining CSS classes.
• Usage: Similar to clsx, but it is older and more widely adopted.
• Advantages: Very popular and widely used. Very similar to clsx in terms of functionality. Supports objects, arrays, and strings.

import classnames from 'classnames';

const buttonClass = classnames('btn', {
  'btn-primary': isPrimary,
  'btn-secondary': isSecondary,
});        

twMerge

• NPM: https://www.npmjs.com/package/tailwind-merge
• Function: twmerge is a utility specific to Tailwind CSS that merges and handles Tailwind classes, automatically resolving conflicts.
• Usage: Combines Tailwind classes so that duplicate classes are resolved correctly (e.g., resolving conflicts between bg-red-500 and bg-blue-500).
• Advantages: Specifically designed for Tailwind CSS. Intelligently resolves class conflicts. Can be used in combination with clsx or classnames to handle conditional classes and then merge the resulting classes.

import { twMerge } from 'tailwind-merge';

const className = twMerge('bg-red-500 text-white', isPrimary && 'bg-blue-500');

// Using with clsx
import clsx from 'clsx';
const className = twMerge(clsx('bg-red-500', {
  'bg-blue-500': isPrimary,
}));        

Comparison

Size:

• clsx and classnames are both very small, but clsx is slightly smaller.
• twMerge is more specific to Tailwind, so it may be slightly larger but solves specific problems that clsx and classnames do not solve on their own.

Adoptability:

• classnames has long been the go-to and has widespread adoption.
• clsx is a more modern, lightweight version but with the same functionality.
• twMerge is less known but essential for projects heavily using Tailwind CSS.

Specificity:

• clsx and classnames are generic and can be used in any React project.
• twMerge is specific to Tailwind CSS and resolves class conflicts better than the other two when working with Tailwind.

Conclusion

If you are working with Tailwind CSS, it is advisable to use twmerge in combination with clsx or classnames to get the best of both worlds: conditional class management and intelligent Tailwind conflict resolution. This approach will help you maintain clean and efficient class handling in your React projects.

Best Solution

Export a utility function that allows the conditional classnames from clsx to be passed into tailwind-merge.

Combining clsx with tailwind-merge allows us to conditionally join Tailwind CSS classes in classNames together without style conflicts.

import { clsx, type ClassValue } from "clsx";
import { twMerge } from "tailwind-merge";
 
function cn(...args: ClassValue[]) {
  return twMerge(clsx(args));
}