Webpack 4 - How to configure minimize?

Question

Webpack 4 comes with the following statement:

Error: webpack.optimize.UglifyJsPlugin has been removed, please use config.optimization.minimize instead.

Fair enough, but I cannot find any information about configuring the UglifyJsPlugin instance running under the hood, for example to change the cache directory. Can this be done?

Solution 1

It's not possible to modify the default configuration.

You can use the optimization.minimizer setting to instantiate your own UglifyJsPlugin, however. Using 4.0 we used this example to get source maps even when mode is set to 'production' for example (no longer necessary as of 4.1.1):

const UglifyJsPlugin = require('uglifyjs-webpack-plugin');

module.exports = {
  optimization: {
    minimizer: [
      // we specify a custom UglifyJsPlugin here to get source maps in production
      new UglifyJsPlugin({
        cache: true,
        parallel: true,
        uglifyOptions: {
          compress: false,
          ecma: 6,
          mangle: true
        },
        sourceMap: true
      })
    ]
  }
};

Solution 2

Without adding uglifyjs-webpack-plugin, you can just add this to the end of your webpack.prod.config.js file:

 optimization: {
   minimize: false
 }

Solution 3

You can try this

npm install uglifyjs-webpack-plugin --save-dev

webpack.config.js

const UglifyJsPlugin = require('uglifyjs-webpack-plugin');

module.exports = {
  optimization: {
    minimizer: [new UglifyJsPlugin()],
  },
};

webpack documentation

Solution 4

Just run:

yarn add uglifyjs-webpack-plugin --dev

Reference: Alfonso Pérez answer

Solution 5

For those coming behind me, realized this misleading error was not related to my correct webpack config, but actually, the offline-plugin was out of date and causing this issue. It needed to be upgraded. See github issue: https://github.com/webpack-contrib/uglifyjs-webpack-plugin/issues/234#issuecomment-369134047

View more solutions

Comments

[connexo]

Wasn't webpack 4 supposed to be zero conf?

[csvan]

This requires me to instantiate the plugin though, I just want to modify existing configuration.

[csvan]

Thanks, but I am looking to modify the default configuration.

[Beau]

@csvan not possible to configure it, have to instantiate your own to specify a custom configuration

[Beau]

@connexo I think the example shown above will be unneeded at some point and that the goal is still zero conf but it's not quite there yet! for reference re: this specific example: github.com/webpack/webpack/issues/6614

[Pierre Trollé]

I did what you said and I got an Error: ReferenceError: UglifyJsPlugin is not defined

[Beau]

@PierreTrollé sorry; I've just added the require line to the example :)

[Alfonso Embid-Desmet]

And keep in mind you might need to do yarn add uglifyjs-webpack-plugin --dev ;)

[Beau]

@Karolis correct, as far as I know the docs are not up to date for Webpack 4.x... this information come from a GitHub issue.

[Beau]

and here; search for "optimization.minimizer" on this page: medium.com/webpack/webpack-4-mode-and-optimization-5423a6bc5‌​97a

[Beau]

one of the GH issues that document this: github.com/webpack/webpack/issues/6879

[Beau]

@AlfonsoPérez webpack already installs uglifyjs-webpack-plugin as a dependency

[Lazerbrains]

I am having this same issue. Just updated from Webpack 3 to 4. When i try to build, it starts but fails at the webpack with the error stated above. I have tried the solution above to no avail. Doesn't fix it, and doesn't give me a different error. Where should this be implemented?

[Mr5o1]

does this answer the question? OP is asking how to configure the plugin, not disable it?

[vir us]

@Mr5o1 stackoverflow is a public community and the OP is not the only person looking at the answers. Google landed me here because the question was related to my search and this answer is a perfectly valid one which helped me resolve my concern. And I'm not the only one like that. I don't really get those types of comments.