No cache in Node.js server

I have read that to avoid caching in Node.js, it is necessary to use:

res.header('Cache-Control', 'no-cache, private, no-store, must-revalidate, max-stale=0, post-check=0, pre-check=0');

But I don't know how to use it because I get errors when I put that line in my code.

My function (where I think I have to program the Cache-Control header) is:

function getFile(localPath, mimeType, res) {
  fs.readFile(localPath, function(err, contents) {
    if (!err) {
      res.writeHead(200, {
        "Content-Type": mimeType,
        "Content-Length": contents.length,
        "Accept-Ranges": "bytes",
      });
      // res.header('Cache-Control', 'no-cache');
      res.end(contents);
    } else {
      res.writeHead(500);
      res.end();
    }
  });
}

Does anyone know how to put no cache in my code?

Make use of a middleware to add no-cache headers. Use this middleware where-ever you intend to turn caching off.

function nocache(req, res, next) {
  res.header('Cache-Control', 'private, no-cache, no-store, must-revalidate');
  res.header('Expires', '-1');
  res.header('Pragma', 'no-cache');
  next();
}

Use the middleware in your routes definition:

app.get('/getfile', nocache, sendContent);

function sendContent(req, res) {
  var localPath = 'some-file';
  var mimeType = '';
  fs.readFile(localPath, 'utf8', function (err, contents) {
    if (!err && contents) {
      res.header('Content-Type', mimeType);
      res.header('Content-Length', contents.length);
      res.end(contents);
    } else {
      res.writeHead(500);
      res.end();
    }
  });
}

Let me know if this works for you.

Set these headers on your response:

'Cache-Control': 'private, no-cache, no-store, must-revalidate'
'Expires': '-1'
'Pragma': 'no-cache'

If you use express you can add this middleware to have no cache on all requests:

// var app = express()
app.use(function (req, res, next) {
    res.header('Cache-Control', 'private, no-cache, no-store, must-revalidate');
    res.header('Expires', '-1');
    res.header('Pragma', 'no-cache');
    next()
});

You've already written your headers. I don't think you can add more after you've done that, so just put your headers in your first object.

res.writeHead(200, {
  'Content-Type': mimeType,
  'Content-Length': contents.length,
  'Accept-Ranges': 'bytes',
  'Cache-Control': 'no-cache'
});

You can use nocache Middleware to turn off caching.

npm install --save nocache

Apply the middleware to your app

const nocache = require('nocache');
...
app.use(nocache());

This disables browser caching.