Extract HLS stream test function

src/utils/mediaSource.ts

@@ -0,0 +1,10 @@
+import type { MediaSourceInfo } from '@jellyfin/sdk/lib/generated-client';
+
+/**
+ * Checks if the media source is an HLS stream.
+ * @param mediaSource The media source.
+ * @returns _true_ if the media source is an HLS stream, _false_ otherwise.
+ */
+export function isHls(mediaSource: MediaSourceInfo|null|undefined): boolean {
+    return (mediaSource?.TranscodingSubProtocol || mediaSource?.Container) === 'hls';
+}