I am using Node/Express to send an mp4 video to the frontend for which I am using angular. The video is being sent smoothly and everything's working perfectly. Now, I want to send the VTT file that contains the subtitles, along with the mp4. I do not know how to do that? I have tried searching but, couldn't find any help. Here's my code:

Node/Express

router.get('/playVideo', (req, res) => {

const path = "videos/testVideo.mp4";
const pathSubtitle = "videos/testsub.vtt";

const stat = fs.statSync(path);
const fileSize = stat.size;

const head = {
  'Content-Length': fileSize,
  'Accept-Ranges' : 'bytes',
  'Content-Type': 'video/mp4'
}

res.writeHead(200, head);
fs.createReadStream(path).pipe(res);
});

Angular

<div class="container-fluid">
<br>
<div class="jumbotron-fluid">

  <video id = "videoPlayer" controls preload = "metadata" style = "width: 
      65%; position: fixed; border: 2px solid #7c2c6c;">
      <source src="http://localhost:3000/playVideo" autoplay type = 
      "video/mp4">
  </video>
  
</div>
</div>

How can I attach the subtitle file with the video response? Or, link to any other documentation that explains that in detail?