fix: Fix targetLang param in rephraseText()

Author: JanEbbing

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 <!-- * add to here... -->
 ### Changed
 * Update form-data lib due to https://github.com/advisories/GHSA-fjxv-7rqg-78g4
+* Fixed `targetLang` parameter in `DeepLClient::rephraseText` to be an optional `string` parameter.
 
 ## [1.19.0] - 2025-06-26
 ### Added

src/deeplClient.ts

@@ -4,7 +4,6 @@
 
 import { Translator, checkStatusCode } from './translator';
 import {
-    SourceLanguageCode,
     DeepLClientOptions,
     WriteResult,
     MultilingualGlossaryDictionaryEntries,
@@ -61,7 +60,7 @@ export class DeepLClient extends Translator {
 
     async rephraseText<T extends string | string[]>(
         texts: T,
-        targetLang: SourceLanguageCode | null,
+        targetLang?: string | null,
         writingStyle?: string | null,
         tone?: string | null,
     ): Promise<T extends string ? WriteResult : WriteResult[]> {

tests/rephraseText.test.ts

@@ -15,6 +15,14 @@ describe('rephrase text', () => {
         expect(result.targetLang).toBe('de');
     });
 
+    withRealServer('should rephrase a single text without a target language', async () => {
+        const deeplClient = makeDeeplClient();
+        const result = await deeplClient.rephraseText(exampleText.de);
+        expect(result.text).toBe(exampleText.de);
+        expect(result.detectedSourceLang).toBe('de');
+        expect(result.targetLang).toBe('de');
+    });
+
     it('should throw an error for unsupported languages', async () => {
         const deeplClient = makeDeeplClient();
         const deeplClientPromise = deeplClient.rephraseText(exampleText.de, 'ja');