add an option to render scss synchronously via renderSync

README.md

@@ -393,6 +393,11 @@ const options = {
   /** Disable a language by setting it to 'false' */
   scss: false,
 
+  /** or pass an option to render synchronously and any other node-sass or sass options*/
+  scss: {
+    renderSync: true
+  },
+
   /**  Pass options to the default preprocessor method */
   stylus: {
     paths: ['node_modules'],

src/transformers/scss.ts

@@ -8,8 +8,25 @@ let sass: {
     options: SassOptions,
     callback: (exception: SassException, result: Result) => void,
   ) => void;
+  renderSync: (
+    options: SassOptions
+  ) => Result;  
 };
 
+type ResolveResult = {
+  code: string;
+  map: string | undefined;
+  dependencies: string[];
+};
+
+function getResultForResolve(result: Result): ResolveResult {
+  return {
+    code: result.css.toString(),
+    map: result.map ? result.map.toString() : undefined,
+    dependencies: result.stats.includedFiles,
+  };
+}
+
 const transformer: Transformer<Options.Sass> = async ({
   content,
   filename,
@@ -19,12 +36,15 @@ const transformer: Transformer<Options.Sass> = async ({
     ({ default: sass } = await importAny('node-sass', 'sass'));
   }
 
-  options = {
-    sourceMap: true,
-    ...options,
-    includePaths: getIncludePaths(filename, options.includePaths),
-    outFile: filename + '.css',
-  };
+  let renderSync: boolean;
+  (
+    {renderSync, ...options} = {
+      sourceMap: true,
+      ...options,
+      includePaths: getIncludePaths(filename, options.includePaths),
+      outFile: filename + '.css',
+    }
+  );
 
   options.data = options.data ? options.data + content : content;
 
@@ -34,14 +54,21 @@ const transformer: Transformer<Options.Sass> = async ({
   }
 
   return new Promise<Processed>((resolve, reject) => {
+    if (renderSync){
+      try {
+        const result = sass.renderSync(options);
+
+        return resolve(getResultForResolve(result));        
+      }
+      catch (err){
+        return reject(err as SassException);
+      }
+    }
+
     sass.render(options, (err, result) => {
       if (err) return reject(err);
 
-      resolve({
-        code: result.css.toString(),
-        map: result.map ? result.map.toString() : undefined,
-        dependencies: result.stats.includedFiles,
-      });
+      resolve(getResultForResolve(result));
     });
   });
 };

src/types/options.ts

@@ -26,7 +26,7 @@ export interface Babel extends BabelOptions {
 }
 
 export type Pug = PugOptions;
-export type Sass = Omit<SassOptions, 'file'>;
+export type Sass = Omit<SassOptions, 'file'> & { renderSync?: boolean };
 // from /~https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/less/index.d.ts#L80
 export interface Less {
   paths?: string[];

test/transformers/scss.test.ts

@@ -4,7 +4,7 @@ import getAutoPreprocess from '../../src';
 import { preprocess } from '../utils';
 
 describe('transformer - scss', () => {
-  it('should prepend scss content via `data` option property', async () => {
+  it('should prepend scss content via `data` option property - via defaul async render', async () => {
     const template = `<style lang="scss"></style>`;
     const opts = getAutoPreprocess({
       scss: {
@@ -15,12 +15,37 @@ describe('transformer - scss', () => {
     expect(preprocessed.toString()).toContain('red');
   });
 
-  it('should return @imported files as dependencies', async () => {
+  it('should return @imported files as dependencies - via default async render', async () => {
     const template = `<style lang="scss">@import "fixtures/style.scss";</style>`;
     const opts = getAutoPreprocess();
     const preprocessed = await preprocess(template, opts);
     expect(preprocessed.dependencies).toContain(
       resolve(__dirname, '..', 'fixtures', 'style.scss').replace(/[\\/]/g, '/'),
     );
   });
+
+  it('should prepend scss content via `data` option property - via renderSync', async () => {
+    const template = `<style lang="scss"></style>`;
+    const opts = getAutoPreprocess({
+      scss: {
+        data: '$color:blue;div{color:$color}',
+        renderSync: true,
+      },
+    });
+    const preprocessed = await preprocess(template, opts);
+    expect(preprocessed.toString()).toContain('blue');
+  });
+
+  it('should return @imported files as dependencies - via renderSync', async () => {
+    const template = `<style lang="scss">@import "fixtures/style.scss";</style>`;
+    const opts = getAutoPreprocess({
+      scss: {
+        renderSync: true,
+      },
+    });
+    const preprocessed = await preprocess(template, opts);
+    expect(preprocessed.dependencies).toContain(
+      resolve(__dirname, '..', 'fixtures', 'style.scss').replace(/[\\/]/g, '/'),
+    );
+  });  
 });