typed-less-modules

Generate TypeScript definitions (.d.ts) files for CSS Modules that are written in LESS (.less). Check out this post to learn more about the rationale and inspiration behind this package.

For example, given the following LESS:

@import (reference) "./variables.less";

.text {
  color: @blue;

  &-highlighted {
    color: @yellow;
  }
}

The following type definitions will be generated:

export const text: string;
export const textHighlighted: string;

Basic Usage

Run with npm package runner:

npx tlm src

Or, install globally:

yarn global add typed-less-modules
tlm src

Or, install and run as a devDependency:

yarn add -D typed-less-modules
yarn tlm src

Advanced Usage

For all possible commands, run tlm --help.

The only required argument is the directoy where all LESS files are located. Running tlm src will search for all files matching src/**/*.less. This can be overridden by providing a glob pattern instead of a directory. For example, tlm src/*.less

--watch (-w)

• Type: boolean
• Default: false
• Example: tlm src --watch

Watch for files that get added or are changed and generate the corresponding type definitions.

--ignoreInitial

• Type: boolean
• Default: false
• Example: tlm src --watch --ignoreInitial

Skips the initial build when passing the watch flag. Use this when running concurrently with another watch, but the initial build should happen first. You would run without watch first, then start off the concurrent runs after.

--includePaths (-i)

• Type: string[]
• Default: []
• Example: tlm src --includePaths src/core

An array of paths to look in to attempt to resolve your @import declarations. This example will search the src/core directory when resolving imports.

--aliases (-a)

• Type: object
• Default: {}
• Example: tlm src --aliases.~some-alias src/core/variables

An object of aliases to map to their corresponding paths. This example will replace any @import '~alias' with @import 'src/core/variables'.

--aliasPrefixes (-p)

• Type: object
• Default: {}
• Example: tlm src --aliasPrefixes.~ node_modules/

An object of prefix strings to replace with their corresponding paths. This example will replace any @import '~bootstrap/lib/bootstrap' with @import 'node_modules/bootstrap/lib/bootstrap'. This matches the common use-case for importing less files from node_modules when less-loader will be used with webpack to compile the project.

--nameFormat (-n)

• Type: "camel" | "kebab" | "param" | "dashes" | "none"
• Default: "camel"
• Example: tlm src --nameFormat camel

The class naming format to use when converting the classes to type definitions.

• camel: convert all class names to camel-case, e.g. App-Logo => appLogo.
• kebab/param: convert all class names to kebab/param case, e.g. App-Logo => app-logo (all lower case with '-' separators).
• dashes: only convert class names containing dashes to camel-case, leave others alone, e.g. App => App, App-Logo => appLogo. Matches the webpack css-loader camelCase 'dashesOnly' option.
• none: do not modify the given class names (you should use --exportType default when using --nameFormat none as any classes with a - in them are invalid as normal variable names). Note: If you are using create-react-app v2.x and have NOT ejected, --nameFormat none --exportType default matches the class names that are generated in CRA's webpack's config.

--listDifferent (-l)

• Type: boolean
• Default: false
• Example: tlm src --listDifferent

List any type definition files that are different than those that would be generated. If any are different, exit with a status code 1.

--exportType (-e)

• Type: "named" | "default"
• Default: "named"
• Example: tlm src --exportType default

The export type to use when generating type definitions.

named

Given the following LESS:

.text {
  color: blue;

  &-highlighted {
    color: yellow;
  }
}

The following type definitions will be generated:

export const text: string;
export const textHighlighted: string;

default

Given the following LESS:

.text {
  color: blue;

  &-highlighted {
    color: yellow;
  }
}

The following type definitions will be generated:

export interface Styles {
  text: string;
  textHighlighted: string;
}

export type ClassNames = keyof Styles;

declare const styles: Styles;

export default styles;

This export type is useful when using kebab (param) cased class names since variables with a - are not valid variables and will produce invalid types or when a class name is a TypeScript keyword (eg: while or delete). Additionally, the Styles and ClassNames types are exported which can be useful for properly typing variables, functions, etc. when working with dynamic class names.

Examples

For examples, see the examples directory:

• Basic Example
• Default Export Example