node-hot-loader

Node Hot Loader

Node Hot Loader is a small tool written on ES2015+ for Hot Module Replacement support for Node.js application development with webpack.

It based on sources of webpack-dev-middleware and webpack/hot/only-dev-server. Under the hood it uses webpack and babel, so you can use all you need configurations in config files for babel and webpack.

The most suitable use case for Node Hot Loader is hot-reloaded express application. Express application can contains API and frontend together, moreover frontend can use own HMR, e.g. React with React Hot Loader. See how to setup React HMR with Express in React Hot Loader docs. Thus, both the frontend and the server will be hot-reloadable.

Node Hot Loader supports webpack config files with ES2015+ (through babel). For using ES2015+ in webpack configuration you must provide .babelrc configuration file in project root directory.

Requirements

Tested with Node.js v7, but must work on previous versions.

Installation

npm install --save-dev node-hot-loader

Usage

Usage: node-hot {options}

Options:
  -c, --config       Webpack config file. If not set then search webpack.config.js in root directory.

Usage example

node-hot --config webpack.config.server.js

You can use all configurations for webpack compiler which webpack supports.

The minimum required configuration:

{
  // It's required!
  // Also if you use multiconfigurations node-hot choose configuration with target 'node'.
  target: 'node',
  
  // node-hot run the last entry which must be the main entry point of node application.
  entry: {
    server: [
      './server/index',
    ],
  },
  
  plugins: [
    // It's required!
    // Enable HMR globally.
    new webpack.HotModuleReplacementPlugin(),
    // It's not necessary.
    // Prints more readable module names in the console on HMR updates.
    new webpack.NamedModulesPlugin(),
    // It's not necessary.
    // In order for don't emit files if errors occurred.
    new webpack.NoEmitOnErrorsPlugin(),
  ],
  
  // It may be necessary when your compiled app uses Webpack too, e.g. for frontend serving,
  //   because Webpack sets __dirname to '/'.
  // It may be some issues in your app, so sets __dirname to false can help you.
  // See https://github.com/webpack/webpack/issues/1599.
  node: {
    __dirname: false,
    __filename: false,
  },
}

Express example

import app from './app'; // configuring express app, e.g. routes and logic
import DB from './services/DB'; // DB service


function startServer() {
  const httpServer = app.listen(app.get('port'), (error) => {
    if (error) {
      console.error(error);
    } else {
      const address = httpServer.address();
      console.info(`==> 🌎 Listening on ${address.port}. Open up http://localhost:${address.port}/ in your browser.`);
    }
  });

  // Hot Module Replacement API
  if (module.hot) {
    let currentApp = app;
    module.hot.accept('./app', () => {
      httpServer.removeListener('request', currentApp);
      import('./app').then(m => {
        httpServer.on('request', m.default);
        currentApp = m.default;
        console.log('Server reloaded!');
      })
      .catch(console.error);
    });
  }
}

// After DB initialized start server
DB.connect()
    .then(() => {
      console.log('Successfully connected to MongoDB. Starting http server...');
      startServer();
    })
    .catch((err) => {
      console.error('Error in server start script.', err);
    });

License

MIT