How to provide your own in-app install experience

Many browsers make it possible for you to enable and promote the installation of your Progressive Web App (PWA) directly within the user interface of your PWA. Installation (sometimes formerly referred to as Add to Home Screen), makes it easy for users to install your PWA on their mobile or desktop device. Installing a PWA adds it to a user's launcher, allowing it to be run like any other installed app.

In addition to the browser provided install experience, it's possible to provide your own custom install flow, directly within your app.

When considering whether to promote install, it's best to think about how users typically use your PWA. For example, if there's a set of users who use your PWA multiple times in a week, these users might benefit from the added convenience of launching your app from a smartphone homescreen or from the Start menu in a desktop operating system. Some productivity and entertainment applications also benefit from the extra screen real-estate created by removing the browser toolbars from the window in installed standalone or minimal-ui modes.

Promoting installation

To indicate your Progressive Web App is installable, and to provide a custom in-app install flow:

1. Listen for the beforeinstallprompt event.
2. Save the beforeinstallprompt event, so it can be used to trigger the install flow later.
3. Alert the user that your PWA is installable, and provide a button or other element to start the in-app installation flow.

Listen for the beforeinstallprompt event

If your Progressive Web App meets the required installation criteria, the browser fires a beforeinstallprompt event. Save a reference to the event, and update your user interface to indicate that the user can install your PWA. This is highlighted below.

// Initialize deferredPrompt for use later to show browser install prompt.
let deferredPrompt;

window.addEventListener('beforeinstallprompt', (e) => {
  // Prevent the mini-infobar from appearing on mobile
  e.preventDefault();
  // Stash the event so it can be triggered later.
  deferredPrompt = e;
  // Update UI notify the user they can install the PWA
  showInstallPromotion();
  // Optionally, send analytics event that PWA install promo was shown.
  console.log(`'beforeinstallprompt' event was fired.`);
});

In-app installation flow

To provide in-app installation, provide a button or other interface element that a user can click to install your app. When the element is clicked, call prompt() on the saved beforeinstallprompt event (stored in the deferredPrompt variable). It shows the user a modal install dialog, asking them to confirm they want to install your PWA.

buttonInstall.addEventListener('click', async () => {
  // Hide the app provided install promotion
  hideInstallPromotion();
  // Show the install prompt
  deferredPrompt.prompt();
  // Wait for the user to respond to the prompt
  const { outcome } = await deferredPrompt.userChoice;
  // Optionally, send analytics event with outcome of user choice
  console.log(`User response to the install prompt: ${outcome}`);
  // We've used the prompt, and can't use it again, throw it away
  deferredPrompt = null;
});

The userChoice property is a promise that resolves with the user's choice. You can only call prompt() on the deferred event once. If the user dismisses it, you'll need to wait until the beforeinstallprompt event is fired again, typically immediately after the userChoice property has resolved.

Detect when the PWA was successfully installed

You can use the userChoice property to determine if the user installed your app from within your user interface. But, if the user installs your PWA from the address bar or other browser component, userChoice won't help. Instead, you should listen for the appinstalled event. It is fired whenever your PWA is installed, no matter what mechanism is used to install your PWA.

window.addEventListener('appinstalled', () => {
  // Hide the app-provided install promotion
  hideInstallPromotion();
  // Clear the deferredPrompt so it can be garbage collected
  deferredPrompt = null;
  // Optionally, send analytics event to indicate successful install
  console.log('PWA was installed');
});

Detect how the PWA was launched

The CSS display-mode media query indicates how the PWA was launched, either in a browser tab, or as an installed PWA. This makes it possible to apply different styles depending on how the app was launched. For example, always hide the install button and provide a back button when launched as an installed PWA.

Track how the PWA was launched

To track how users launch your PWA, use matchMedia() to test the display-mode media query. Safari on iOS doesn't support this yet, so you must check navigator.standalone, it returns a boolean indicating whether the browser is running in standalone mode.

function getPWADisplayMode() {
  const isStandalone = window.matchMedia('(display-mode: standalone)').matches;
  if (document.referrer.startsWith('android-app://')) {
    return 'twa';
  } else if (navigator.standalone || isStandalone) {
    return 'standalone';
  }
  return 'browser';
}

Track when the display mode changes

To track if the user changes between standalone, and browser tab, listen for changes to the display-mode media query.

window.matchMedia('(display-mode: standalone)').addEventListener('change', (evt) => {
  let displayMode = 'browser';
  if (evt.matches) {
    displayMode = 'standalone';
  }
  // Log display mode change to analytics
  console.log('DISPLAY_MODE_CHANGED', displayMode);
});

Update UI based on the current display mode

To apply a different background color for a PWA when launched as an installed PWA, use conditional CSS:

@media all and (display-mode: standalone) {
  body {
    background-color: yellow;
  }
}

Updating your app's icon and name

What if you need to update your app name, or provide new icons? Check out How Chrome handles updates to the web app manifest to see when and how are those changes are reflected in Chrome.