webpack.config.dev.js

const path = require('path');
const webpack = require('webpack');
const webpackMerge = require('webpack-merge'); // used to merge webpack configs
const commonConfig = require('./webpack.config.common.js'); // the settings that are common to prod and dev

//

module.exports = function(options) {

    const ENV = options.ENV || 'development';
    const PORT = options.PORT || 8888;

    return webpackMerge(commonConfig, {
        // debug: true,
        devtool: 'source-map',
        plugins: [
            new webpack.HotModuleReplacementPlugin(),
            new webpack.DefinePlugin({
                'ENV': JSON.stringify(ENV)
            })
        ],
        resolve: {
            extensions: ['.js', '.ts']
        },
        devServer: {
            port: PORT,
//            hot: true,
            inline: true,
            historyApiFallback: true
        },
    });
};