Add minified version

[bennycode]

    new webpack.optimize.UglifyJsPlugin({
      compress: {
        warnings: false,
        screw_ie8: true,
        conditionals: true,
        unused: true,
        comparisons: true,
        sequences: true,
        dead_code: true,
        evaluate: true,
        if_return: true,
        join_vars: true
      },
      output: {
        comments: false
      },
    })

[bennycode]

Solution: http://stackoverflow.com/a/37762405/451634

[bennycode]

Another valid option:

var path = require('path');
var webpack = require('webpack');
var UnminifiedWebpackPlugin = require('unminified-webpack-plugin');

module.exports = {
    entry: {
        index: './src/index.js'
    },
    output: {
        path: path.resolve(__dirname, 'dist'),
        filename: 'library.min.js'
    },
    plugins: [
        new webpack.optimize.UglifyJsPlugin({
            compress: {
                warnings: false
            }
        }),
        new UnminifiedWebpackPlugin()
    ]
};