Exporting a class with Webpack and Babel not working

As Matias points out, webpack must be configured to export the default in order to avoid your client code doing const MyLibrary = require('MyLibrary').default

In 2021, using webpack 5, the correct config is:

module.exports = {
    
    output: {
        filename: '[name].bundle.js',
        library: {
            name: 'MyLibrary',
            type: 'umd',
            export: 'default' //<--- important
        },
    },

    // specify entry and other configs per usual..
}

ref: https://webpack.js.org/configuration/output/#outputlibraryexport

Default exports are stored in the default property of the module. If you want to make your library accessible without users having to know that, you can change your webpack entry file to

module.exports = require('./libraryfile').default;

Also, make sure you have library: 'YourLibraryName' in your webpack config as per webpack.github.io/docs/configuration.html#output-library.

Webpack has changed a lot, now you can get the same results as the Felix Kling answer but with webpack config. You should add the libraryExport key in the output config and set it to "default". That would set your main class as the root content of your library. Here are the docs.

Your webpack config should be like this:

module.exports = {
  entry: {
    pentagine: "./lib/pentagine.js",
    demos: ["./demos/helicopter_game/PlayState.js"]
  },

  output: {
    path: __dirname,
    filename: "./build/[name].js",
    libraryTarget: 'umd',
    libraryExport: 'default' //<-- New line
  },

  module: {
    loaders: [
      {
        test: /.js$/,
        loader: 'babel-loader',
        exclude: /node_modules/,
        query: {
          presets: ['es2015']
        }
      }
    ]
  }
};