feat: add outputFile for typescript etc

src/utilities/writeIndex.js

@@ -18,7 +18,7 @@ export default (directoryPaths, options = {}) => {
     const optionsWithConfig = Object.assign({}, options, {config});
     const siblings = readDirectory(directoryPath, optionsWithConfig);
     const indexCode = createIndexCode(siblings, optionsWithConfig);
-    const indexFilePath = path.resolve(directoryPath, 'index.js');
+    const indexFilePath = path.resolve(directoryPath, optionsWithConfig.outputFile || 'index.js');
 
     fs.writeFileSync(indexFilePath, indexCode);
   });

src/utilities/writeIndexCli.js

@@ -27,7 +27,7 @@ export default (directoryPaths, options = {}) => {
   if (options.updateIndex || options.recursive) {
     sortedDirectoryPaths = _.map(sortedDirectoryPaths, (dir) => {
       return findIndexFiles(dir, {
-        fileName: options.updateIndex ? 'index.js' : '*',
+        fileName: options.updateIndex ? options.outputFile || 'index.js' : '*',
         silent: options.updateIndex || options.ignoreUnsafe
       });
     });