Content-Type set by other middleware gets overwritten

[dmohns]

• Operating System: macOS 10.14.3
• Node Version: v11.10.0
• NPM Version: 6.8.0
• webpack version: 4.29.6
• webpack-dev-middleware Version: 3.6.0

• This is a feature request
• This is a bug

Code

I am working with a custom middleware to serve static assets from their gzipped versions, like so:

app.use(function (req, res, next) {
  if (req.url.endsWith('css')) {
    req.url = req.url + '.gz';
    res.set('Content-Encoding', 'gzip');
    res.set('Content-Type', 'text/css');
  }
  next()
});

Unfortunately, webpack-dev-middleware overwrites Content-Type regardless of whether or not it's been set already by another middleware. See

webpack-dev-middleware/lib/middleware.js

Line 82 in e5bd8f8

res.setHeader('Content-Type', contentType);

Expected Behavior

In the resulting request: Content-Type: text/css

Actual Behavior

In the resulting request: Content-Type: application/gzip; charset=UTF-8

For Bugs; How can we reproduce the behavior?

For Features; What is the motivation and/or use-case for the feature?

[dmohns]

@clshortfuse you had some trouble with incorrect mimeTypes set by webpack-dev-middleware. Is this problem similar?

[alexander-akait]

We should add check if header already exists, feel free to send a PR with fix 👍

[alexander-akait]

Release https://github.com/webpack/webpack-dev-middleware/releases/tag/v3.6.1