webpack.config.js

const path = require("path");
const autoprefixer = require("autoprefixer");

// Do this as the first thing so that any code reading it knows the right env.
process.env.BABEL_ENV = "production";
process.env.NODE_ENV = "production";

module.exports = {
  entry: "./src/lib/index.tsx",
  output: {
    path: path.resolve(__dirname, "build"),
    filename: "index.js",
    libraryTarget: "commonjs2"
  },
  resolve: {
    extensions: [".tsx", ".ts", ".js"],
    modules: [path.resolve("./src/lib"), path.resolve("./node_modules")],
    alias: {
      // my alias
      utils: path.resolve(__dirname, "./src/utils/index.js")
    }
  },
  module: {
    rules: [
      {
        test: /\.ts|tsx?$/,
        include: path.resolve(__dirname, "src"),
        exclude: /(node_modules|bower_components|build)/,
        loaders: ["ts-loader"]
      },
      {
        test: /\.scss$/,
        include: path.resolve(__dirname, "src"),
        use: [
          {
            loader: "style-loader" // creates style nodes from JS strings
          },
          {
            loader: "css-loader" // translates CSS into CommonJS
          },
          {
            loader: "sass-loader" // compiles Sass to CSS
          }
        ]
      },
      {
        test: /\.css$/,
        use: [
          {
            loader: "style-loader"
          },
          {
            loader: "css-loader"
          },
          {
            loader: "postcss-loader",
            options: {
              // Necessary for external CSS imports to work
              // https://github.com/facebookincubator/create-react-app/issues/2677
              ident: "postcss",
              plugins: () => [
                require("postcss-flexbugs-fixes"),
                autoprefixer({
                  browsers: [
                    ">1%",
                    "last 4 versions",
                    "Firefox ESR",
                    "not ie < 9" // React doesn't support IE8 anyway
                  ],
                  flexbox: "no-2009"
                })
              ]
            }
          }
        ]
      }
    ]
  },
  externals: {
    react: "commonjs react",
    "react-dom": "commonjs react-dom"
  }
};