# PWA Install Handler

[![npm version](https://img.shields.io/npm/v/pwa-install-handler.svg)](https://www.npmjs.com/package/pwa-install-handler)
[![License: ISC](https://img.shields.io/npm/l/pwa-install-handler.svg)](https://opensource.org/licenses/ISC)

Handling PWA installation prompt made easier. This library provides a simple interface to the `beforeinstallprompt` event, allowing you to create a custom install button for your Progressive Web App.

## Features

- **Easy to use:** Simple API to handle the PWA installation flow.
- **Lightweight:** Tiny footprint with zero dependencies.
- **Typed:** Written in TypeScript for a better developer experience.

## Installation

```sh
npm install pwa-install-handler
```

## Usage

### HTML

First, you need a button in your HTML that will trigger the installation prompt. Initially, it should be hidden.

```html
<button id="installButton" style="display: none;">Install</button>
```

### JavaScript

Then, in your JavaScript, you can use `pwaInstallHandler` to show the button when the app is installable and to trigger the prompt when the button is clicked.

```javascript
import { pwaInstallHandler } from 'pwa-install-handler'

const $installButton = document.querySelector('#installButton')

pwaInstallHandler.addListener((canInstall) => {
	$installButton.style.display = canInstall ? 'inline-block' : 'none'
})

$installButton.addEventListener('click', () => {
	pwaInstallHandler.install()
})
```

### Screencast

![UI example](https://raw.githubusercontent.com/FilipChalupa/pwa-install-handler/HEAD/screencast.gif)

### Demo

Check out the [live demo](https://filipchalupa.cz/pwa-install-handler/) or the [source code](https://github.com/FilipChalupa/pwa-install-handler/tree/main/demo).

## API

### Methods

| Method             | Signature                                           | Description                                                                                            |
| ------------------ | --------------------------------------------------- | ------------------------------------------------------------------------------------------------------ |
| `install()`        | `() => Promise<boolean>`                            | Triggers the installation prompt. Returns a promise that resolves to `true` if the app is installed.   |
| `addListener()`    | `(callback: (canInstall: boolean) => void) => void` | Adds a listener that is called when the installability state changes. The callback receives a boolean. |
| `removeListener()` | `(callback: (canInstall: boolean) => void) => void` | Removes a previously added listener.                                                                   |
| `canInstall()`     | `() => boolean`                                     | Returns `true` if the app is ready to be installed.                                                    |
| `getEvent()`       | `() => BeforeInstallPromptEvent \| null`            | Returns the internal `BeforeInstallPromptEvent` object.                                                |

### `BeforeInstallPromptEvent`

The `getEvent()` method returns a `BeforeInstallPromptEvent` object, which has the following properties:

| Property     | Type                           | Description                                                      |
| ------------ | ------------------------------ | ---------------------------------------------------------------- |
| `prompt()`   | `() => Promise<void>`          | Shows the installation prompt to the user.                       |
| `userChoice` | `Promise<{ outcome: string }>` | A promise that resolves when the user interacts with the prompt. |

## Browser Support

The `beforeinstallprompt` event is not supported by all browsers. You can check the latest browser support on [caniuse.com](https://caniuse.com/#feat=mdn-api_beforeinstallpromptevent).

When the event is not supported, `canInstall` will always be `false`.

## Requirements for Installability

For the `beforeinstallprompt` event to be fired, your PWA must meet certain requirements. These requirements are browser-specific. You can learn more about them here:

- [MDN: Installable PWAs](https://developer.mozilla.org/en-US/docs/Web/Progressive_web_apps/Installable_PWAs#Requirements)
- [web.dev: Install criteria](https://web.dev/articles/install-criteria)

## Contributing

Contributions are welcome! Please open an issue or submit a pull request on our [GitHub repository](https://github.com/FilipChalupa/pwa-install-handler).

## License

This project is licensed under the ISC License. See the [LICENSE](LICENSE) file for details.