Unwanted charset=UTF-8 always added to custom mime types

[gpoitch]

• Operating System: macOS 10.14
• Node Version: 10.4.1
• NPM Version: 6.4.1
• webpack version: 4.27.1
• webpack-dev-middleware Version: 3.4.0

• This is a feature request
• This is a bug

Since #136, charset=UTF-8 is always appended to the Content-Type header. If I define custom mime types, I believe that this shouldn't be appended.

For example, mobile safari can render 3d/AR models in a native viewer when a file is served with model/vnd.pixar.usd. When setting the option mimeTypes: { 'model/vnd.pixar.usd', ['usdz'] }, the server will return: Content-Type: model/vnd.pixar.usd; charset=UTF-8. The addition of the charset causes the browser to incorrectly interpret the mime type.

This is already special-cased for wasm.

Expected Behavior

charset=UTF-8 is not appended to every Content-Type header when defining custom mimeTypes.

Actual Behavior

charset=UTF-8 is always appended

I can make a PR if you agree on the proposed behavior.

[alexander-akait]

@gpoitch hm, sound reasonable, any ideas how we can detect when we need add charset when not?

[gpoitch]

@evilebottnawi yes, after some digging looks like it should be added only if charset is defined for the type in mime-db (https://github.com/jshttp/mime-db/blob/master/db.json). We could conditionally add charset based on that instead.

[alexander-akait]

@gpoitch 👍 PR welcome and when we release new version

[gpoitch]

#351

[alexander-akait]

/cc @hiroppy I think we should not change logic, same logic using in many places in express and express middleware https://github.com/expressjs/serve-index/blob/master/index.js#L543, i think will be great implement an option for this

[hiroppy]

hmm, it seems we need to overwrite below lines.

  res.setHeader('Content-Type', type + '; charset=utf-8')
  res.setHeader('Content-Length', Buffer.byteLength(body, 'utf8'))

  // body
  res.end(body, 'utf8')

Yes, I agree with you. We need to provide a new option for overwriting this.

[hiroppy]

ok, I'll take over this.

[alexander-akait]

Just for information, https://github.com/expressjs/serve-static/blob/master/index.js do not use utf8, maybe we should investigate deeply

[hiroppy]

This problem seems to be difficult because express is writing utf-8 directly.😥

[alexander-akait]

Fixed in next