Functional typed classnames for TailwindCSS

tailwindcss-classnames

TailwindCSS is a CSS library that has gained a lot of traction. The developer experience is pretty epic and you ensure a low footprint on your css by composing existing classes for most of your css.

So why mess with it?

TailwindCSS is based on strings and with some nice tooling on top like TailwindCSS VSCode extension you get a pretty descent experience. That said, there are limitations to a purely declarative approach of strings. When using tailwindcss-classnames you will get additional power in the form of:

• Validation of classnames: You can not write the wrong classname, cause the API only allows you to insert valid classnames
• Functional approach: Since we are working in Typescript we get more freedom in using functional powers like composition and dynamic composition
• Defining by variables: Even though it is nice to write TailwindCSS inline with your elements, it does not scale. You want to move definitions outside of the component for reusability and composition
• Support for all editors and IDEs: Because it's just TypeScript types, you get these powers in all editors and IDEs that support TypeScript.

You can not get this experience using pure TailwindCSS and the VSCode extension, but you do get it with tailwindcss-classnames.

Install

Please follow the guide to set up TailwindCSS. Now do:

npm install tailwindcss-classnames

⚠️ NOTE: This project versions match with TailwindCSS versions except for semver patch releases

The project is literally the classnames project with custom typing. That means it arrives at your browser at approximately 484b minified and gzipped (bundlephobia).

Create classes

import {classnames} from 'tailwindcss-classnames';

classnames('border-none', 'rounded-sm');

The arguments passed to classnames is typed, which means you get discoverability. You can even search for the supported classes:

Dynamic classes

Since we are using classnames you can also add your classes dynamically:

import {classnames} from 'tailwindcss-classnames';

classnames('border-none', 'rounded-sm', {
  ['bg-gray-200']: true,
});

Composing classes

Even though classnames just returns a string, it is a special typed string that you can compose into other definitions.

import {classnames} from 'tailwindcss-classnames';

export const button = classnames('border-none', 'rounded-sm');

export const redButton = classnames(button, 'bg-red-100');

Using with React

Since React has excellent typing support I want to give an example of how you could use it.

// styles.ts
import {classnames} from 'tailwindcss-classnames';

export const form = classnames('container', 'w-full');

export const button = classnames('border-none', 'rounded-sm');

export const alertButton = classnames(button, 'bg-red-100');

export const disabled = classnames('opacity-25', 'bg-gray-100');

export const submitButton = (disabled: boolean) =>
  classnames(styles.button, {
    [styles.disabled]: disabled,
  });

// App.tsx
import * as React from 'react';
import * as styles from './styles';

export const App: React.FC<{disabled}> = ({disabled}) => {
  return (
    <form className={styles.form}>
      <button type="submit" className={styles.submitButton(disabled)}>
        Submit
      </button>
      <button className={styles.alertButton}>Cancel</button>
    </form>
  );
};

Using the CLI

The types included in this package are the default tailwindcss classes, but if you modified your tailwind config file and/or want to add external custom classes, you can use the CLI tool to do this.

CLI arguments

• -i, --input Name or relative path of the TailwindCSS config file (if not provided, tries to find 'tailwind.config.js')
• -o, --output Name or relative path of the generated types file (optional, default: "tailwindcss-classnames.ts")
• -x, --extra Name or relative path of the file with the custom extra types (optional)
• -h, --help display help for command

Example of CLI usage

Add the CLI to npm scripts in your package.json then run npm run generate-css-types or yarn generate-css-types:

"scripts": {
  "generate-css-types": "tailwindcss-classnames -i path/to/tailwind.config.js -o path/to/output-file.ts"
}

⚠️ NOTE: that if you want to add custom types from external file, the type must be a default export:

export default MyCustomType;
type MyCustomType =
  | "btn"
  | "sidebar"
  ...

Known limitiations

• Relative imports inside the config does not work. use __dirname instead. See #120 for details.
• Don't run as npx tailwindcss-classnames. Use as an npm script as mentioned above.
• Limited support for the JIT engine (#204).
• Backlog

Any help with these issues is very much appreciated.