The fastest and tiniest utility for conditionally joining classNames.

npm install classix

Use any amount of string expressions and classix will join them like so:

import cx from "classix";
// or
import { cx } from "classix";

cx("class1", "class2");
// => "class1 class2"

cx("class1 class2", "class3", "class4 class5");
// => "class1 class2 class3 class4 class5"

cx("class1", true && "class2");
// => "class1 class2"

cx(false && "class1", "class2");
// => "class2"

cx(true ? "class1" : "class2");
// => "class1"

cx("class1", false ? "class2" : "class3");
// => "class1 class3"

cx(...["class1", "class2", "class3"]);
// => class1 class2 class3

cx(
  "flex",
  isPrimary ? "bg-primary-100" : "bg-secondary-100",
  isLarge ? "m-4 p-4" : "m-2 p-2",
);
// => "flex bg-primary-100 m-2 p-2" *assuming isPrimary is true and isLarge is false

Compared to other libraries, classix only allows string expressions as arguments:

// 🚫
clsx({ "class-1": isPrimary });
// ✅
cx(isPrimary && "class-1");

// 🚫
clsx({ "class-1": isPrimary && isLarge, "class-2": !isPrimary || !isLarge });
// ✅
cx(isPrimary && isLarge ? "class-1" : "class-2");

String expressions have a few benefits over objects:

• A faster typing experience
• A more intuitive syntax (conditions first)
• else support through ternary operators

What's more, by leveraging them, classix provides:

• A simpler and consistent API
• A smaller library size
• Better performance

Sources: classix, clsx, classnames

Sources: Ran benchmark on an AMD Ryzen 5 5600x with Node 20.

• Supports all major browsers
• Supports all versions of Node.js
• Works with both ES Modules and CommonJS
• Zero dependencies
• Fully typed with TypeScript
• Fully tested
• Semver compliant

If you are using classnames or clsx, you can migrate to classix by changing your imports:

- import classnames from 'classnames';
+ import cx from 'classix';

And if you were using object arguments, you'll have to convert them to string arguments:

- classnames({ 'class-1': cond1, 'class-2': cond2 });
+ cx(cond1 && 'class-1', cond2 && 'class-2')

That's it!

"This looks great. I agree that the object notation is not great and not worth the perf hit." — @jmeistrich

"It looks good! I like the idea that you can’t pass objects and is simple and minimal. I will use it on my next application instead of classnames." — @m0ment98

"Thank you for creating and maintaining this package! It is great." — @charkour

For a list of changes and releases, see the changelog.

Found a bug, have a question or looking to improve classix? Open an issue, start a discussion or submit a PR!