typed-css-modules

typed-css-modules

Creates TypeScript definition files from CSS Modules .css files.

If you have the following css,

/* styles.css */

@value primary: red;

.myClass {
  color: primary;
}

typed-css-modules creates the following .d.ts files from the above css:

/* styles.css.d.ts */
declare const styles: {
  readonly primary: string;
  readonly myClass: string;
};
export = styles;

So, you can import CSS modules' class or variable into your TypeScript sources:

/* app.ts */
import styles from './styles.css';
console.log(`<div class="${styles.myClass}"></div>`);
console.log(`<div style="color: ${styles.primary}"></div>`);

CLI

npm install -g typed-css-modules

And exec tcm <input directory> command. For example, if you have .css files under src directory, exec the following:

tcm src

Then, this creates *.css.d.ts files under the directory which has the original .css file.

(your project root)
- src/
    | myStyle.css
    | myStyle.css.d.ts [created]

output directory

Use -o or --outDir option.

For example:

tcm -o dist src

(your project root)
- src/
    | myStyle.css
- dist/
    | myStyle.css.d.ts [created]

file name pattern

By default, this tool searches **/*.css files under <input directory>. If you can customize the glob pattern, you can use --pattern or -p option. Note the quotes around the glob to -p (they are required, so that your shell does not perform the expansion).

tcm -p 'src/**/*.css' .

watch

With -w or --watch, this CLI watches files in the input directory.

validating type files

With -l or --listDifferent, list any files that are different than those that would be generated. If any are different, exit with a status code 1.

camelize CSS token

With -c or --camelCase, kebab-cased CSS classes(such as .my-class {...}) are exported as camelized TypeScript variable name(export const myClass: string).

You can pass --camelCase dashes to only camelize dashes in the class name. Since version 0.27.1 in the webpack css-loader. This will keep upperCase class names intact, e.g.:

.SomeComponent {
  height: 10px;
}

becomes

declare const styles: {
  readonly SomeComponent: string;
};
export = styles;

See also webpack css-loader's camelCase option.

named exports (enable tree shaking)

With -e or --namedExports, types are exported as named exports as opposed to default exports. This enables support for the namedExports css-loader feature, required for webpack to tree shake the final CSS (learn more here).

Use this option in combination with https://webpack.js.org/loaders/css-loader/#namedexport and https://webpack.js.org/loaders/style-loader/#namedexport (if you use style-loader).

When this option is enabled, the type definition changes to support named exports.

NOTE: this option enables camelcase by default.

.SomeComponent {
  height: 10px;
}

Standard output:

declare const styles: {
  readonly SomeComponent: string;
};
export = styles;

Named exports output:

export const someComponent: string;

arbitrary file extensions

With -a or --allowArbitraryExtensions, output filenames will be compatible with the "arbitrary file extensions" feature that was introduce in TypeScript 5.0. See the docs for more info.

In essence, the *.css.d.ts extension now becomes *.d.css.ts so that you can import CSS modules in projects using ESM module resolution.

API

npm install typed-css-modules

import DtsCreator from 'typed-css-modules';
let creator = new DtsCreator();
creator.create('src/style.css').then(content => {
  console.log(content.tokens); // ['myClass']
  console.log(content.formatted); // 'export const myClass: string;'
  content.writeFile(); // writes this content to "src/style.css.d.ts"
});

class DtsCreator

DtsCreator instance processes the input CSS and creates TypeScript definition contents.

new DtsCreator(option)

You can set the following options:

• option.rootDir: Project root directory(default: process.cwd()).
• option.searchDir: Directory which includes target *.css files(default: './').
• option.outDir: Output directory(default: option.searchDir).
• option.camelCase: Camelize CSS class tokens.
• option.namedExports: Use named exports as opposed to default exports to enable tree shaking. Requires import * as style from './file.module.css'; (default: false)
• option.allowArbitraryExtensions: Output filenames that will be compatible with the "arbitrary file extensions" TypeScript feature
• option.EOL: EOL (end of line) for the generated d.ts files. Possible values '\n' or '\r\n'(default: os.EOL).

create(filepath, contents) => Promise(dtsContent)

Returns DtsContent instance.

• filepath: path of target .css file.
• contents(optional): the CSS content of the filepath. If set, DtsCreator uses the contents instead of the original contents of the filepath.

class DtsContent

DtsContent instance has *.d.ts content, final output path, and function to write the file.

writeFile(postprocessor) => Promise(dtsContent)

Writes the DtsContent instance's content to a file. Returns the DtsContent instance.

• postprocessor (optional): a function that takes the formatted definition string and returns a modified string that will be the final content written to the file.

  You could use this, for example, to pass generated definitions through a formatter like Prettier, or to add a comment to the top of generated files:

  dtsContent.writeFile(definition => `// Generated automatically, do not edit\n${definition}`);
  

tokens

An array of tokens is retrieved from the input CSS file. e.g. ['myClass']

contents

An array of TypeScript definition expressions. e.g. ['export const myClass: string;'].

formatted

A string of TypeScript definition expressions.

e.g.

export const myClass: string;

messageList

An array of messages. The messages contain invalid token information. e.g. ['my-class is not valid TypeScript variable name.'].

outputFilePath

Final output file path.

Remarks

If your input CSS file has the following class names, these invalid tokens are not written to output .d.ts file.

/* TypeScript reserved word */
.while {
  color: red;
}

/* invalid TypeScript variable */
/* If camelCase option is set, this token will be converted to 'myClass' */
.my-class {
  color: red;
}

/* it's ok */
.myClass {
  color: red;
}

Example

There is a minimum example in this repository example folder. Clone this repository and run cd example; npm i; npm start.

Or please see https://github.com/Quramy/typescript-css-modules-demo. It's a working demonstration of CSS Modules with React and TypeScript.

License

This software is released under the MIT License, see LICENSE.txt.