webpack 4: access the mode flag from webpack.config.js file

Do you want to request a feature or report a bug?

feature

If this is a feature request, what is motivation or use case for changing the behavior?

Since webpack 4 introduces an official --mode it’d be nice to be able to access it, otherwise I’m back to the old process.env.NODE_ENV === 'production' if I want to customize the production build, like for https://github.com/webpack/webpack/issues/6409#issuecomment-361636056

Please mention other relevant information such as the browser version, Node.js version, webpack version and Operating System.

webpack 4.0.0-beta.0

[fregante]

This seems to work correctly with --mode production, -p and <no flag>. 🎉 for normalized argv

module.exports = (env, argv) => ({
	...etc,
	optimization: {
		minimize: false,
		minimizer: argv.mode === 'production' ? [
			new UglifyJsPlugin(...customConfig)
		] : []
	}
});

Are there any caveats to using a function? Like subtle changes of behavior?

[bengrunfeld]

Just to clarify for all those a little who need a little extra explanation (I fall into that camp).

webpack --mode development 

webpack.config.js

module.exports = (env, argv) => {
  console.log(argv.mode)        // outputs development
  return {
    // All your other custom config...
  }
}