Using Frontend Libraries

You can build Neutralinojs apps with vanilla JavaScript or using any frontend library. This tutorial guides you to set up your favorite frontend library for Neutralinojs application development.

Initializing projects#

First, you need to create a new empty Neutralinojs project. Use the neutralinojs/neutralinojs-zero template to create an empty project, as shown below.

neu create myapp --template neutralinojs/neutralinojs-zero

Now, create a new project with your favorite frontend framework's command-line tools. In this tutorial, we are going to use React, but you can use any frontend library as you wish. You need to create this project inside the myapp directory.

cd myapp
npx create-react-app myapp-react

Configuring Neutralinojs project#

The neutralinojs-zero template has a pre-included HTML file and icon, so delete the www directory since we don't need those files now.

rm -rf www

You need to configure the Neutralinojs project to support the frontend framework. First, you can set the document root with your frontend framework's build directory. React typically generates build outputs to build directory, so we can update documentRoot as follows.

"documentRoot": "/myapp-react/build/"

Now, our Neutralinojs app knows the application resource location, but it's missing an icon, so set an icon for the app. You can load an icon from your frontend framework's default resources directory. For demonstration purposes, let's use the React icon from the public directory.

  "modes": {
    "window": {
      // --- other options
      "icon": "/myapp-react/public/logo192.png"
    }
  }

Configuring neu CLI#

neu CLI wants to know about the client library location and resources directory to run neu run and neu update commands properly. Store client library into your frontend framework's static resources directory and set application resources path with the same value you've used for documentRoot.

We can configure CLI for React by using the following options.

  "cli": {
    // --- other options
    "resourcesPath": "/myapp-react/build/",
    "clientLibrary": "/myapp-react/public/neutralino.js",
  }

When we modify cli.clientLibrary property, we need to enter neu update to get the client library to the new location. Go to myapp and update the client library.

neu update

Now, you can build and run the React application as a Neutralinojs application — it's possible with the following steps.

First, build the React application with the following command.

cd myapp-react
npm run build

Finally, run the Neutralinojs application.

cd ..
neu run

Configuring the frontend app#

You could run the application with the neu run command, but you can't use the native API yet since the React application doesn't load the client library. Add a <script> tag and load the client library from your frontend library's main HTML file.

React typically holds the main HTML file content in the ./public/index.html file, so we can put the following HTML snippet there to load the client library.

<script src="%PUBLIC_URL%/neutralino.js"></script>

Also, make sure to initialize the client library from your frontend application's entry point. React's application entry-point is typically ./src/index.js. Therefore, we can do the initialization process from there.

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';

ReactDOM.render(
  <React.StrictMode>
    <App />
  </React.StrictMode>,
  document.getElementById('root')
);

window.Neutralino.init(); // Add this function call

Now, build and run your application again with the inspector window.

neu run -- --window-enable-inspector

Try entering some native API calls from the browser console.

Enabling hot-reload#

Building every code change and testing your application is undoubtedly time-consuming. Therefore, you can use your frontend framework's HMR (Hot Module Replacement) features to speed up your development activities. But, we have a small issue here. There are now two HTTP servers: the Neutralinojs resource server and the frontend framework's development server. How can we load the Neutralinojs client library from the frontend framework's development server?

Don't worry — neu CLI provides a built-in feature to enable HMR by patching the main HTML file. You can add the following section to your configuration file for activating hot-reloading.

  "cli": {
    // --- other options
    "frontendLibrary": {
        "patchFile": "/myapp-react/public/index.html",
        "devUrl": "http://localhost:3000"
    }
  }
}

The above options tell neu CLI about the main HTML file and development server URL.

Now, start your frontend development server. In React, we can do it with the following command.

npm start

Finally, run the Neutralinojs application with the following command.

neu run --frontend-lib-dev

Make sure to build your frontend app once before entering the above command since it loads the client library from the Neutralinojs application resources directory (not from your frontend framework's directory).

See the full source code of this tutorial here.