Why is the final bundle not compressed in webpack2+uglifyjs-webpack-plugin?

Question

JavaScript

bundle.js just doesn't compress. I do not know why. It seems that uglifyjs has been added to the plugins.
Here is webpack.config.js:

const path = require("path");
const webpack = require("webpack");
const HtmlWebpackPlugin = require('html-webpack-plugin');
const UglifyJSPlugin = require('uglifyjs-webpack-plugin');

module.exports = {
  entry: "./src/index",
  output: {
    filename: "bundle.js",
    path: path.join(__dirname, "dist")
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        loader: 'babel-loader',
        exclude: /node_modules/,
        query: { presets: ['stage-3', 'react'] }
      }, {
        test: /\.css$/,
        include: path.join(__dirname, "src", "styles", "css"),
        use: ['style-loader', 'css-loader']
      }, {
        test: /\.(scss|sass)$/,
        include: path.join(__dirname, "src", "styles", "sass"),
        use: ['style-loader', 'css-loader', 'sass-loader',]
      },
      { test: /\.(png|svg|jpg|jpeg|gif)$/, use: ['file-loader',] },
      { test: /\.(woff|woff2|eot|ttf|otf)$/, use: ['file-loader',] },
    ]
  },
  plugins: [
    new HtmlWebpackPlugin({
      inject: false,
      template: './src/index.ejs',
      title_: "webpack test react"
    }),
    new webpack.optimize.CommonsChunkPlugin({
      children: true,
      async: true,
    }),
    new UglifyJSPlugin({
      test: [".js"],
      include: path.join(__dirname, "src"),
      exclude: /node_modules/,
    })
  ]
}

Answer 1

Why didn't the standard UglifyJsPlugin fit out of the box?
I have this config - everything works fine:

const { optimize } = require('webpack');
const { UglifyJsPlugin } = optimize;

new UglifyJsPlugin({
    beautify: false,
    comments: false,
    mangle: {
        screw_ie8: true,
        keep_fnames: true
    },
    compress: {
        screw_ie8: true,
        sequences: true,
        booleans: true,
        loops: true,
        unused: true,
        warnings: false,
        drop_console: true,
        unsafe: true
    }
})