When building a React application, we often need to determine className dynamically based on certain conditions. The clsx library simplifies this process and makes the code cleaner and more readable.

Installation

To use it, first install it with npm, yarn, or pnpm:

npm install clsx
# or
yarn add clsx
# or
pnpm add clsx

You can learn more about clsx on its official GitHub repository: clsx on GitHub

How to Use

With clsx, we can manage class names conditionally without writing long and cluttered code.

Basic Example

import clsx from "clsx";

const Button = ({ primary }: { primary: boolean }) => {
  return (
    <button
      className={clsx("btn", {
        "btn-primary": primary,
        "btn-secondary": !primary,
      })}
    >
      Click me
    </button>
  );
};

In this example:

• If primary is true, the className becomes "btn btn-primary".
• If primary is false, the className becomes "btn btn-secondary".

Combining Multiple Classes

You can also combine classes from various conditions:

const isActive = true;
const isDisabled = false;

const className = clsx(
  "base-class",
  isActive && "active-class",
  isDisabled ? "disabled-class" : "enabled-class"
);

console.log(className); // Output: "base-class active-class enabled-class"

Using clsx with Tailwind CSS

If you are using Tailwind CSS, it is recommended to use tailwind-merge alongside clsx to avoid conflicting classes:

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

const buttonClass = twMerge(
  clsx("p-4 text-white", isActive && "bg-blue-500", isDisabled && "opacity-50")
);

<button className={buttonClass}>Click me</button>;

With twMerge, conflicting classes (such as p-2 and p-4) are filtered so that only the most relevant class is applied.

You can learn more about tailwind-merge here: tailwind-merge on GitHub

Conclusion

Using clsx helps make className management cleaner and more flexible. If you use Tailwind CSS, tailwind-merge is highly recommended to ensure that classes do not conflict. With this approach, your React code becomes more organized and easier to maintain.