feat: allow a function to be used for lessOptions (#325)

Author: Ryan Clark

README.md

@@ -49,7 +49,7 @@ The `less-loader` requires [less](https://github.com/less/less.js) as [`peerDepe
 
 ### `lessOptions`
 
-Type: `Object`
+Type: `Object|Function`
 
 You can pass any Less specific options to the `less-loader` through the `lessOptions` property in the [loader options](https://webpack.js.org/configuration/module/#rule-options-rule-query). See the [Less documentation](http://lesscss.org/usage/#command-line-usage-options) for all available options in dash-case. Since we're passing these options to Less programmatically, you need to pass them in camelCase here:
 

src/getLessOptions.js

@@ -10,12 +10,20 @@ import createWebpackLessPlugin from './createWebpackLessPlugin';
  * @returns {Object}
  */
 function getLessOptions(loaderContext, loaderOptions) {
+ const options = clone(
+ loaderOptions.lessOptions
+ ? typeof loaderOptions.lessOptions === 'function'
+ ? loaderOptions.lessOptions(loaderContext) || {}
+ : loaderOptions.lessOptions
+ : {}
+ );
+
  const lessOptions = {
  plugins: [],
  relativeUrls: true,
  // We need to set the filename because otherwise our WebpackFileManager will receive an undefined path for the entry
  filename: loaderContext.resourcePath,
- ...(loaderOptions.lessOptions ? clone(loaderOptions.lessOptions) : {}),
+ ...options,
  };
 
  if (typeof lessOptions.paths === 'undefined') {

src/options.json

@@ -2,12 +2,19 @@
  "type": "object",
  "properties": {
  "lessOptions": {
- "description": "Options to pass through to `less`. (https://github.com/webpack-contrib/less-loader#examples).",
- "type": "object",
- "additionalProperties": true
+ "description": "Options to pass through to `less`. (https://github.com/webpack-contrib/less-loader#lessoptions).",
+ "anyOf": [
+ {
+ "type": "object",
+ "additionalProperties": true
+ },
+ {
+ "instanceof": "Function"
+ }
+ ]
  },
  "sourceMap": {
- "description": "Enables/Disables generation of source maps (https://github.com/webpack-contrib/less-loader#source-maps).",
+ "description": "Enables/Disables generation of source maps (https://github.com/webpack-contrib/less-loader#sourcemap).",
  "type": "boolean"
  }
  },

test/index.test.js

@@ -128,6 +128,16 @@ test("should resolve all imports from the given paths using Less' resolver", asy
  });
 });
 
+test('should allow a function to be passed through for `lessOptions`', async () => {
+ await compileAndCompare('import-paths', {
+ lessLoaderOptions: {
+ lessOptions: () => ({
+ paths: [__dirname, nodeModulesPath],
+ }),
+ },
+ });
+});
+
 test('should add all resolved imports as dependencies, including those from the Less resolver', async () => {
  const dependencies = [];