Add named exports output format

README.md

@@ -29,7 +29,7 @@ So, you can import CSS modules' class or variable into your TypeScript sources:
 
 ```ts
 /* app.ts */
-import * as styles from './styles.css';
+import styles from './styles.css';
 console.log(`<div class="${styles.myClass}"></div>`);
 console.log(`<div style="color: ${styles.primary}"></div>`);
 ```
@@ -102,11 +102,45 @@ webpack `css-loader`. This will keep upperCase class names intact, e.g.:
 becomes
 
 ```typescript
-export const SomeComponent: string;
+declare const styles: {
+  readonly "SomeComponent": string;
+};
+export = styles;
 ```
 
 See also [webpack css-loader's camelCase option](https://github.com/webpack/css-loader#camelcase).
 
+#### 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](https://webpack.js.org/loaders/css-loader/#namedexport)).
+
+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.*
+
+```css
+.SomeComponent {
+  height: 10px;
+}
+```
+
+**Standard output:**
+
+```typescript
+declare const styles: {
+  readonly "SomeComponent": string;
+};
+export = styles;
+```
+
+**Named exports output:**
+
+```typescript
+export const someComponent: string;
+```
+
 ## API
 
 ```sh
@@ -133,6 +167,7 @@ You can set the following options:
 * `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.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)`
@@ -182,7 +217,7 @@ e.g. `['my-class is not valid TypeScript variable name.']`.
 Final output file path.
 
 ## Remarks
-If your input CSS file has the followng class names, these invalid tokens are not written to output `.d.ts` file.
+If your input CSS file has the following class names, these invalid tokens are not written to output `.d.ts` file.
 
 ```css
 /* TypeScript reserved word */

example/package.json

@@ -4,8 +4,8 @@
   "description": "",
   "main": "app.js",
   "scripts": {
-    "tcm": "node ../lib/cli.js -p style01.css",
-    "tcmw": "node ../lib/cli.js -w -p style01.css",
+    "tcm": "node ../lib/cli.js -e -p style01.css",
+    "tcmw": "node ../lib/cli.js -e -w -p style01.css",
     "compile": "npm run tcm && ./node_modules/.bin/tsc -p .",
     "bundle": "npm run compile && ./node_modules/.bin/browserify -o bundle.js -p [ css-modulesify -o bundle.css ] app.js",
     "start": "npm run bundle && node bundle.js"

src/cli.ts

@@ -14,6 +14,7 @@ const yarg = yargs.usage('Create .css.d.ts from CSS modules *.css files.\nUsage:
   .alias('o', 'outDir').describe('o', 'Output directory').string("o")
   .alias('w', 'watch').describe('w', 'Watch input directory\'s css files or pattern').boolean('w')
   .alias('c', 'camelCase').describe('c', 'Convert CSS class tokens to camelcase').boolean("c")
+  .alias('e', 'namedExports').describe('e', 'Use named exports as opposed to default exports to enable tree shaking.').boolean("e")
   .alias('d', 'dropExtension').describe('d', 'Drop the input files extension').boolean('d')
   .alias('s', 'silent').describe('s', 'Silent output. Do not show "files written" messages').boolean('s')
   .alias('h', 'help').help('h')
@@ -45,6 +46,7 @@ async function main(): Promise<void> {
     outDir: argv.o,
     watch: argv.w,
     camelCase: argv.c,
+    namedExports: argv.e,
     dropExtension: argv.d,
     silent: argv.s
   });

src/dts-content.ts

@@ -4,18 +4,22 @@ import * as path from "path";
 import isThere from "is-there";
 import * as mkdirp from 'mkdirp';
 import * as util from "util";
+import camelcase from "camelcase";
 
 const writeFile = util.promisify(fs.writeFile);
 const readFile = util.promisify(fs.readFile);
 
+export type CamelCaseOption = boolean | 'dashes' | undefined;
+
 interface DtsContentOptions {
     dropExtension: boolean;
     rootDir: string;
     searchDir: string;
     outDir: string;
     rInputPath: string;
     rawTokenList: string[];
-    resultList: string[];
+    namedExports: boolean;
+    camelCase: CamelCaseOption;
     EOL: string;
 }
 
@@ -26,6 +30,8 @@ export class DtsContent {
     private outDir: string;
     private rInputPath: string;
     private rawTokenList: string[];
+    private namedExports: boolean;
+    private camelCase: CamelCaseOption;
     private resultList: string[];
     private EOL: string;
 
@@ -36,8 +42,19 @@ export class DtsContent {
         this.outDir = options.outDir;
         this.rInputPath = options.rInputPath;
         this.rawTokenList = options.rawTokenList;
-        this.resultList = options.resultList;
+        this.namedExports = options.namedExports;
+        this.camelCase = options.camelCase;
         this.EOL = options.EOL;
+
+        // when using named exports, camelCase must be enabled by default
+        // (see https://webpack.js.org/loaders/css-loader/#namedexport)
+        // we still accept external control for the 'dashes' option,
+        // so we only override in case is false or undefined
+        if (this.namedExports && !this.camelCase) {
+            this.camelCase = true;
+        }
+
+        this.resultList = this.createResultList();
     }
 
     public get contents(): string[] {
@@ -46,6 +63,14 @@ export class DtsContent {
 
     public get formatted(): string {
         if(!this.resultList || !this.resultList.length) return '';
+
+        if (this.namedExports) {
+            return [
+                ...this.resultList.map(line => 'export ' + line),
+                ''
+            ].join(os.EOL) + this.EOL;
+        }
+
         return [
             'declare const styles: {',
             ...this.resultList.map(line => '  ' + line),
@@ -92,6 +117,39 @@ export class DtsContent {
             await writeFile(this.outputFilePath, finalOutput, 'utf8');
         }
     }
+
+    private createResultList(): string[] {
+        const convertKey = this.getConvertKeyMethod(this.camelCase);
+
+        const result = this.rawTokenList
+            .map(k => convertKey(k))
+            .map(k => !this.namedExports ? 'readonly "' + k + '": string;' : 'const ' + k + ': string;')
+
+        return result;
+    }
+
+    private getConvertKeyMethod(camelCaseOption: CamelCaseOption): (str: string) => string {
+        switch (camelCaseOption) {
+          case true:
+            return camelcase;
+          case 'dashes':
+            return this.dashesCamelCase;
+          default:
+            return (key) => key;
+        }
+      }
+
+      /**
+       * Replaces only the dashes and leaves the rest as-is.
+       *
+       * Mirrors the behaviour of the css-loader:
+       * https://github.com/webpack-contrib/css-loader/blob/1fee60147b9dba9480c9385e0f4e581928ab9af9/lib/compile-exports.js#L3-L7
+       */
+      private dashesCamelCase(str: string): string {
+        return str.replace(/-+(\w)/g, function(match, firstLetter) {
+          return firstLetter.toUpperCase();
+        });
+      }
 }
 
 function removeExtension(filePath: string): string {

src/dts-creator.ts

@@ -1,19 +1,17 @@
 import * as process from 'process';
 import * as path from'path';
 import * as os from 'os';
-import camelcase from "camelcase"
 import FileSystemLoader from './file-system-loader';
-import {DtsContent} from "./dts-content";
+import {DtsContent, CamelCaseOption} from "./dts-content";
 import {Plugin} from "postcss";
 
 
-type CamelCaseOption = boolean | 'dashes' | undefined;
-
 interface DtsCreatorOptions {
   rootDir?: string;
   searchDir?: string;
   outDir?: string;
   camelCase?: CamelCaseOption;
+  namedExports?: boolean;
   dropExtension?: boolean;
   EOL?: string;
   loaderPlugins?: Plugin<any>[];
@@ -26,7 +24,8 @@ export class DtsCreator {
   private loader: FileSystemLoader;
   private inputDirectory: string;
   private outputDirectory: string;
-  private camelCase: boolean | 'dashes' | undefined;
+  private camelCase: CamelCaseOption;
+  private namedExports: boolean;
   private dropExtension: boolean;
   private EOL: string;
 
@@ -39,6 +38,7 @@ export class DtsCreator {
     this.inputDirectory = path.join(this.rootDir, this.searchDir);
     this.outputDirectory = path.join(this.rootDir, this.outDir);
     this.camelCase = options.camelCase;
+    this.namedExports = !!options.namedExports;
     this.dropExtension = !!options.dropExtension;
     this.EOL = options.EOL || os.EOL;
   }
@@ -59,20 +59,15 @@ export class DtsCreator {
       const tokens = res;
       const keys = Object.keys(tokens);
 
-      const convertKey = this.getConvertKeyMethod(this.camelCase);
-
-      const result = keys
-        .map(k => convertKey(k))
-        .map(k => 'readonly "' + k + '": string;')
-
       const content = new DtsContent({
         dropExtension: this.dropExtension,
         rootDir: this.rootDir,
         searchDir: this.searchDir,
         outDir: this.outDir,
         rInputPath,
         rawTokenList: keys,
-        resultList: result,
+        namedExports: this.namedExports,
+        camelCase: this.camelCase,
         EOL: this.EOL
       });
 
@@ -81,29 +76,4 @@ export class DtsCreator {
       throw res;
     }
   }
-
-  private getConvertKeyMethod(camelCaseOption: CamelCaseOption): (str: string) => string {
-    switch (camelCaseOption) {
-      case true:
-        return camelcase;
-      case 'dashes':
-        return this.dashesCamelCase;
-      default:
-        return (key) => key;
-    }
-  }
-
-  /**
-   * Replaces only the dashes and leaves the rest as-is.
-   *
-   * Mirrors the behaviour of the css-loader:
-   * https://github.com/webpack-contrib/css-loader/blob/1fee60147b9dba9480c9385e0f4e581928ab9af9/lib/compile-exports.js#L3-L7
-   */
-  private dashesCamelCase(str: string): string {
-    return str.replace(/-+(\w)/g, function(match, firstLetter) {
-      return firstLetter.toUpperCase();
-    });
-  }
-
-
 }

src/run.ts

@@ -14,6 +14,7 @@ interface RunOptions {
     outDir?: string;
     watch?: boolean;
     camelCase?: boolean;
+    namedExports?: boolean;
     dropExtension?: boolean;
     silent?: boolean;
 }
@@ -26,6 +27,7 @@ export async function run(searchDir: string, options: RunOptions = {}): Promise<
         searchDir,
         outDir: options.outDir,
         camelCase: options.camelCase,
+        namedExports: options.namedExports,
         dropExtension: options.dropExtension,
     });
 

test/dts-creator.spec.ts

@@ -109,6 +109,32 @@ declare const styles: {
 };
 export = styles;
 
+`
+        );
+        done();
+      });
+    });
+
+    it('returns named exports formatted .d.ts string', done => {
+      new DtsCreator({ namedExports: true }).create('test/testStyle.css').then(content => {
+        assert.equal(
+          content.formatted,
+          `\
+export const myClass: string;
+
+`
+        );
+        done();
+      });
+    });
+
+    it('returns camelcase names when using named exports as formatted .d.ts string', done => {
+      new DtsCreator({ namedExports: true }).create('test/kebabedUpperCase.css').then(content => {
+        assert.equal(
+          content.formatted,
+          `\
+export const myClass: string;
+
 `
         );
         done();