Native App Install Prompt

The native app install prompt gives you the ability to let users quickly and seamlessly install your native app on their device directly from the app store, without leaving the browser, and without showing an annoying interstitial.

# What are the criteria?

In order to show the native app install prompt to the user, your site must meet the following criteria:

• Neither the web app nor the native app currently installed on the device.
• Includes a Web App Manifest that includes:
  • short_name
  • name (used in the banner prompt)
  • icons including a 192px and a 512px version
  • prefer_related_applications is true
  • related_applications object with information about the app
• Served over HTTPS

A beforeinstallprompt event will fire when you meet these criteria. You can use it to prompt the user to install your native app.

# Required manifest properties

To prompt the user to install your native app, you need to add two properties to your web app manifest, prefer_related_applications and related_applications.

"prefer_related_applications": true,
"related_applications": [
    {
    "platform": "play",
    "id": "com.google.samples.apps.iosched"
    }
]

# prefer_related_applications

The prefer_related_applications property tells the browser to prompt the user with your native app instead of the web app. If you leave this value unset, or false, the browser will prompt the user to install the web app instead.

# related_applications

related_applications is an array with a list of objects that tell the browser about your preferred native application. Each object must include a platform property and an id property. Where the platform is play and the id is your Play Store app ID.

# Show the install prompt

In order to show the install dialog, you need to:

1. Listen for the beforeinstallprompt event.
2. Notify the user your native app can be installed with a button or other element that will generate a user gesture event.
3. Show the prompt by calling prompt() on the saved beforeinstallprompt event.

# Listen for beforeinstallprompt

If the criteria are met, Chrome will fire a beforeinstallprompt event. You can use it to indicate your app can be installed, and then prompt the user to install it.

When the beforeinstallprompt event has fired, save a reference to the event, and update your user interface to indicate that the user can install your app.

let deferredPrompt;

window.addEventListener('beforeinstallprompt', (e) => {
  // Prevent Chrome 67 and earlier from automatically showing the prompt
  e.preventDefault();
  // Stash the event so it can be triggered later.
  deferredPrompt = e;
});

# Notify the user your app can be installed

The best way to notify the user your app can be installed is by adding a button or other element to your user interface. Don't show a full page interstitial or other elements that may be annoying or distracting.

window.addEventListener('beforeinstallprompt', (e) => {
  // Prevent Chrome 67 and earlier from automatically showing the prompt
  e.preventDefault();
  // Stash the event so it can be triggered later.
  deferredPrompt = e;
  // Update UI notify the user they can add to home screen
  btnAdd.style.display = 'block';
});

# Show the prompt

To show the install prompt, call prompt() on the saved event from within a user gesture. It will show a modal dialog, asking the user to add your app to their home screen.

Then, listen for the promise returned by the userChoice property. The promise returns an object with an outcome property after the prompt has shown and the user has responded to it.

btnAdd.addEventListener('click', (e) => {
  // hide our user interface that shows our A2HS button
  btnAdd.style.display = 'none';
  // Show the prompt
  deferredPrompt.prompt();
  // Wait for the user to respond to the prompt
  deferredPrompt.userChoice
    .then((choiceResult) => {
      if (choiceResult.outcome === 'accepted') {
        console.log('User accepted the A2HS prompt');
      } else {
        console.log('User dismissed the A2HS prompt');
      }
      deferredPrompt = null;
    });
});

You can only call prompt() on the deferred event once. If the user dismisses it, you'll need to wait until the beforeinstallprompt event fires on the next page navigation.

# Special considerations for when using content security policy

If your site has a restrictive Content Security Policy, make sure to add *.googleusercontent.com to the img-src directive so Chrome can download the icon associated with your app from the Play Store.

In some cases *.googleusercontent.com maybe more verbose than desired. It's possible to narrow this down by remote debugging an Android device to determine the URL of the app icon.