Allow setting default mime-type from webpack config.

[grosscol]

Feature Proposal

Configuration option to set default mime-type

// webpack.dev.js
module.exports = {
  devServer: {
    devMiddleWare: {
      // provide default when mime-type evals to false.
      mimeTypeDefault: 'text/html'
    }
  }
}

Stack overflow issue detailing the context in which this use case arose: https://stackoverflow.com/questions/70011373/how-to-configure-webpack-dev-server-to-serve-extensionless-files-as-text-html

Feature Use Case

For developing applications with pages that don't have a file extension. E.g. localhost:8080/example. It would be convenient to be able to specify a default mime-type for files that don't have a file extension; specifically, 'text/html'.

Current State

The express server will emit this content type as application/octet-stream even though middleware goes out of it's way to avoid inappropriately setting a mime-type at middleware.js#L104-L113. Express uses mime 1.6 which eventually fills in a default type at mine.js#L69-L73 The result being there is a default content type, and it's determined further down in the stack.

In production deployment this is not a problem. Configuring production web servers to emit the desired mime type, re-writing the requests, or specifying the mime-type in metadata makes this not a production issue.

Please paste the results of npx webpack-cli info here, and mention other relevant information

∫ wp5-extensionless/webpack-boilerplate (main)⮞ npx webpack-cli info

  System:
    OS: Linux 5.11 Ubuntu 20.04.3 LTS (Focal Fossa)
    CPU: (4) x64 Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz
    Memory: 11.16 GB / 31.31 GB
  Binaries:
    Node: 16.13.0 - /usr/bin/node
    npm: 8.1.0 - /usr/bin/npm
  Browsers:
    Firefox: 94.0
  Packages:
    babel-loader: ^8.2.2 => 8.2.2 
    clean-webpack-plugin: ^4.0.0 => 4.0.0 
    copy-webpack-plugin: ^9.0.1 => 9.0.1 
    css-loader: ^6.4.0 => 6.4.0 
    css-minimizer-webpack-plugin: ^3.1.1 => 3.1.1 
    eslint-import-resolver-webpack: ^0.13.1 => 0.13.1 
    html-webpack-plugin: ^5.3.2 => 5.3.2 
    postcss-loader: ^6.2.0 => 6.2.0 
    sass-loader: ^12.2.0 => 12.2.0 
    style-loader: ^3.3.0 => 3.3.0 
    webpack: ^5.58.2 => 5.58.2 
    webpack-cli: ^4.9.0 => 4.9.0 
    webpack-dev-server: ^4.3.1 => 4.3.1 
    webpack-merge: ^5.8.0 => 5.8.0 

[alexander-akait]

PR welcome