No cache in Node.js server

Question

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?

Use [`res.header()`](http://expressjs.com/api.html#res.set) (and/or [`res.setHeader()`](http://nodejs.org/api/http.html#http_response_setheader_name_value)) before [`res.writeHead()`](http://nodejs.org/api/http.html#http_response_writehead_statuscode_reasonphrase_headers) if you want to mix them. `writeHead()` is final, so no additional headers can be added after it. — Jonathan Lonowski, Dec 06 '13 at 17:14
hi thanks.. I have tried to put res.header() before but I got error. On the other hand res.setHeader seems to work — user2986808, Dec 09 '13 at 08:45

score 149 · Answer 1 · answered Dec 06 '13 at 17:23

149

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.

answered Dec 06 '13 at 17:23

vmx

7,989
4
22
20

He's not using Express. – Brad Dec 07 '13 at 00:37
Hi vmx... thanks but Brad is right I am not using Express and I think your answer is useful using only Express... – user2986808 Dec 09 '13 at 08:32
1

Ok, even if you aren't using express, what essentially needed is to set the nocache headers. I'm adding the headers in a reusable middleware, otherwise you can set those headers in any way that works. – vmx Dec 09 '13 at 08:44
6

I don't think using or not using express matters, here. – vmx Dec 09 '13 at 08:45

score 54 · Answer 2 · answered May 26 '15 at 08:23

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()
});

How is this different/an improvement over @vmx 's answer? – umasudhan May 31 '18 at 01:53 — umasudhan, May 31 '18 at 01:53

score 32 · Accepted Answer · answered Dec 06 '13 at 17:12

32

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'
});

answered Dec 06 '13 at 17:12

Brad

159,648
54
349
530

If you use `res.set` you can set headers after *written your headers*, before `res.write` fires, may have changed since '13 – Lawrence Cherone Sep 21 '19 at 16:44

score 9 · Answer 4 · answered Aug 21 '18 at 03:51

9

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.

answered Aug 21 '18 at 03:51

Lanil Marasinghe

2,785
24
24

score 2 · Answer 5 · answered Aug 24 '16 at 21:44

Pylinux's answer worked for me, but upon further inspection, I found the helmet module for express that handles some other security features for you.

http://webapplog.com/express-js-security-tips/

To use, install and require helmet in express.js, then call app.use(helmet.noCache());

score 0 · Answer 6 · answered Sep 18 '15 at 21:36

0

After spelunking through source code for the express and fresh modules, this works from the server side (before res.end is called):

req.headers['if-modified-since'] = undefined;
req.headers['if-none-match'] = undefined;

Nasty, but it works.

answered Sep 18 '15 at 21:36

Dale Anderson

1,681
16
15

No cache in Node.js server

6 Answers6

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