Question

How can I implement file streaming in an Express.js server?

I'm looking to implement file streaming in an Express.js server to handle large files efficiently without loading them fully into memory. I’d like to understand the process and the best practices, especially for streaming video or large data files to clients. What’s the right way to set up file streaming in an Express.js application?

Answer 1

To carry out this file streaming scheme in an Express.js server, we utilize Node.js's fs.createReadStream() methods. This technique opens up large files sequentially, enabling the efficient transfer of data and allowing users to start using the content without waiting for a full download

// 1. Set up the necessary modules:
const express = require('express');
const fs = require('fs');
const path = require('path');

const app = express();

// Port configuration
const PORT = 3000;

// 2. Create a route to handle file streaming:
app.get('/stream/:filename', (req, res) => {
  const filePath = path.join(__dirname, 'files', req.params.filename);

  // Check if the file exists
  if (!fs.existsSync(filePath)) {
    return res.status(404).send('File not found');
  }

  // Get file stats (size, etc.)
  const stat = fs.statSync(filePath);

  // Set response headers for streaming
  res.writeHead(200, {
    'Content-Type': 'video/mp4', // Adjust this for different file types
    'Content-Length': stat.size,
  });

  // Create a read stream from the file
  const readStream = fs.createReadStream(filePath);

  // Pipe the read stream to the response object
  readStream.pipe(res);
});

// 3. Example endpoints to demonstrate the streaming
// This will serve different types of files from the 'files' directory.
// Make sure to have example files in the 'files' directory like 'video.mp4' and 'audio.mp3'.

app.get('/', (req, res) => {
  res.send(`
    <h1>File Streaming Server</h1>
    <p>Use the following routes to stream files:</p>
    <ul>
      <li><a href="/stream/video.mp4">Stream video.mp4</a></li>
      <li><a href="/stream/audio.mp3">Stream audio.mp3</a></li>
    </ul>
  `);
});

// 4. Start the server
app.listen(PORT, () => {
  console.log(`Server is running on http://localhost:${PORT}`);
});