create-sveltekit-eel-app

SvelteKitEel App

CLI to start an Eel app with SvelteKit.

npm create sveltekit-eel-app@latest

About

create-sveltekit-eel-app is a CLI to create all the boilerplate needed for a lightweight Eel app with SvelteKit integration. It was created to make simple desktop GUI applications. As the name implies, this combines two main technologies:

• Eel: A Python library for "making simple Electron-like offline HTML/JS GUI apps."
• SvelteKit: "A framework for rapidly developing robust, performant web applications using Svelte"
  • SvelteKit will be running in SPA mode.

This template also comes with Tailwind CSS preconfigured.

Requirements

• Chrome or Microsoft Edge
• git
• npm
• node ≥ 16
• Python ≥ 3.10 (lower versions have not been tested)

Usage

Get started with:

npm create sveltekit-eel-app@latest

After it's done setting up, you can optionally create a virtual environment for your Python dependencies. Then,

cd your-app-name
pip3 install -r requirements.txt

Start the app with

npm run start:eel

Development

You can always preview the full app and test Eel-SvelteKit connections with

npm run start:eel

Develop the SvelteKit GUI with

npm run dev

And restart npm run start:eel as needed.

Currently, npm run start:eel-dev will try to serve the eel app using the src folder but exposed functions will not work - so it's better to go with the above workflow.

List of commands

npm run

• dev: Starts the SvelteKit site in dev mode.
• build: Builds the SvelteKit app into a folder build.
• preview: Previews the SvelteKit app in build.
• test: Run playwright tests.
• check: Run svelte-check against your project.
• check:watch: Same as the above command but with --watch.
• test:unit: Run vitest tests.
• lint: Run linting.
• format: Format files with Prettier.
• start:eel: Starts the Eel app. The SvelteKit app is served through the build folder.
• start:eel-nb: Starts the Eel app with no build step for the SvelteKit app beforehand.
• start:eel-dev: Starts the Eel app in dev mode. The SvelteKit app is served through your src folder. SvelteKit also needs to run for this to work. SEE THE NOTE ABOUT DEV MODE BELOW
• build:eel-generate-spec: This should be used the first time you create a production build of your Eel app. Generates a .spec file along with the build.
• build:eel: Create a production build of your Eel app according to the generated .spec file.

Note on developing with create-sveltekit-eel

There are currently some issues that prevent a better developer experience - specifically, hot-reloading the eel app with SvelteKit does not seem to work right now for Eel exposed functions.

This means that calling any functions exposed by Eel may not work as intended.

If you'd still like to continue, you can run

npm run start:eel-dev

To start up an Eel app in development mode. The window will pop up, and you may see an error similar to this:

This site can’t be reached
localhost refused to connect.

Which is expected. Then, start up your SvelteKit app with

npm run dev

Go back to your Eel app and you should see everything now. You can develop like this if you want to test anything that doesn't involve exposed Eel functions. The Python app always needs to be restarted for changes to take effect.

Distributing

The first time you create a production build of your Eel app, you need to run

npm run build:eel-generate-spec

This will create a .spec file along with the build. You can test out the application by running the executable in the dist folder.

In subsequent builds, you can run

npm run build:eel

Which will generate a production build according to the provided .spec file. For example, you may want to turn on the console window, or change the icon, or make the entire project a single file. Log output is not currently available in the console for production builds to ensure compatibility with the --noconsole setting, see here.

You can always manually run pyinstaller with

pyinstaller eelApp.spec --clean --onefile

The example above generates a single file executable.

Note that pyinstaller does not support cross-platform builds. If you want to deploy your app on Linux and Windows, you need pipelines to install pyinstaller and build the app for each platform.

Chrome and Edge warning

Eel will open a Chrome window by default, and will try to open a Microsoft Edge window on Windows operating systems if Chrome is not found. This means if your end user has none of these browsers installed, the app will not work.

Examples

You can view the examples on Eel for an idea on how to use it.

This template comes with basic examples of communicating between Python and SvelteKit. Here are some things you can look at:

<script>
...

function hello_from_sk(name: string) {
    message = `Hello ${name}, this function is being called from Python [${count}]`;
    count++;
}
if (eel) {
    window.eel.expose(hello_from_sk, 'hello_from_sk');
}

...
</script>

This exposes a function to your Python backend that can be called with eel.hello_from_sk(name). You can modify elements such as the message or count variables in your SvelteKit app whenever it's called.

You can also deal with functions asynchronously with callbacks. Say you exposed a function that lets you pick a file from your computer:

def choose_file() -> str:
    tkinter.Tk().withdraw()
    root = tkinter.Tk()
    root.attributes("-alpha", 0.0)
    root.attributes("-topmost", True)
    filename = fd.askopenfilename(
        parent=root, title="Choose a file", filetypes=[("All files", "*.*")]
    )
    root.destroy()
    return filename

This returns the filename at some point. In your SvelteKit application, call the exposed function like so:

eel?.choose_file()((file: string) => {
  // handle the selected file
  message = `File selected: ${file}`;
});

The callback function will be called when the Python function returns.