webpack.config.js

const path = require("path");
const CopyWebpackPlugin = require("copy-webpack-plugin");

module.exports = {
    entry: "./app/javascripts/app.js",
    output: {
        path: path.resolve(__dirname, "build"),
        filename: "app.js"
    },
    plugins: [
        // Copy our app's index.html to the build folder.
        new CopyWebpackPlugin([{ from: "./app/index.html", to: "index.html" }])
    ],
    module: {
        rules: [
            {
                test: /\.css$/,
                use: ["style-loader", "css-loader"]
            },
            {
                test: /\.(ttf|eot|woff|woff2|svg)/,
                use: ["file-loader"]
            }
        ],
        loaders: [
            { test: /\.json$/, use: "json-loader" },
            {
                test: /\.js$/,
                exclude: /(node_modules|bower_components)/,
                loader: "babel-loader",
                query: {
                    presets: ["es2015"],
                    plugins: ["transform-runtime"]
                }
            }
        ]
    }
};