Am I inside in-app browser

Series of tests to detect an in-app browser (aka WebViews) and to escape from it.

Introduction

Either due a lack of features or even by simply not sharing the cookies and other forms of storage with the default browser in mobile devices, working with in-app browsers are usually not a good experience for web developers and for the final user as well.

This repository is a study of attemps to:

1. Detect if the page is inside a in-app browser
2. Open a link outside of it

Detection

Attempt 1: https://github.com/f2etw/detect-inapp

Attempt 2: https://gist.github.com/BorisChumichev/7c0ea033daf33da73306a396ffa174d1

Attempt 3: https://developers.whatismybrowser.com/api/docs/v2/

Attempt 4: https://www.npmjs.com/package/is-ua-webview

Notes about detection

3 of 4 attemps here uses the user-agent as base for detection. Some applications that has this feature built changes the user-string to contain the name of the app, which makes this detection much more easier.

The last one take in account the width/height proportions of a window opened in Safari app and the Safari in-app browser.

Escape

Attempt 1: anchor tag with target _system, trying to mimic cordova functionality into the browser:

<a href="https://http.cat" target="_system">Link 1</a>

Attempt 2: Variant of attempt 1 using window.open() instead of a anchor tag, also using the third argument of it to force a new window:

<button onClick={() => window.open('https://http.cat', '_system', 'location=yes')}>Link 2</button>

Attempt 3: Using a Google Chrome deep link:

// for android
<a href="googlechrome://navigate?url=http.cat" target="_system">Link 3</a>
// for iOS
<a href="googlechrome://http.cat" target="_system">Link 4</a>

Attempt 4: Using android intents:

// android only
<a
	href='intent://navigate?url=www.http.cat#Intent;scheme=;package=com.android.browser;S.browser_fallback_url=http%3A%2F%2Fhttp.cat;end'
	target='_system'
>
	Link 5
</a>

Results

Is the in-app browser detectable?

App/OS	LinkedIn	Facebook	Facebook Messenger	Instagram
Android	No*	Yes	Yes	Yes
iOS	Yes	Yes	Yes	Yes

LinkedIn For android does not use a custom instance of a WebView. It uses whatever the default browser is, keeping the storage, which is great.

WhatIsMyBrowser API (detection attempt 3) gave the same results as the simpler implementations.

Is the in-app browser escapable?

Only using chrome deep links (escape attempt 3). Currently all the other attemps failed.

window.open(), anchor tags with target='_blank', target='_system' opens the other window within the same instance.

safari://url deep link does not work.

intent:// for android devices goes to Google Play Store with a spinner loading indefinitely (maybe I got the implementation wrongly).

This means that a explicit approach needs to be used in order to open another app inside a in-app browser. However, that does not work for Safari, which is a bummer.

In statistics by StatCounter it gives you what is the market share of browsers, chrome being at ~64%. So, if you implement this functionality to escape from a in-app browser, you have this porcentage of chance to make it work. I'm interested this proportion is the same for iOS devices only, since Safari is more a common browser used in this system, something that these statistics does not provide.

I have to state that I do not agree with this implementation since it reinforces the Google monopoly over the Web.

Questions without answers

• How's the process of build a in-app browser functionality works and what's the effort to change the user-agent string to contain your app name with the version build number?
• Is it possible to have a "general" deep link generation that opens an URL in the default mobile browser? Like an intent for android development but for mobile web?
• How GitHub website/app does deep linking redirect? If u click in the "source code" link in the demo, it will open the GitHub app if you have that installed. In the anchor href there's no mention to the app whatsoever.

References

https://leemartin.dev/twitter-please-identify-yourself-in-your-app-webview-user-agent-4f58dbadfa05

https://leemartin.dev/in-app-browsers-i-forgive-thee-not-f87b25f9418e

https://mobiforge.com/research-analysis/webviews-and-user-agent-strings

https://www.stoutner.com/the-x-requested-with-header/

https://developer.chrome.com/docs/multidevice/android/intents/

https://developer.apple.com/forums/thread/105641

https://blog.branch.io/technical-guide-to-android-chrome-intents/

https://twitter.com/NolanOBrien/status/1129041460026859520

SO Threads:

https://stackoverflow.com/questions/51917577/deep-link-to-open-safari-from-another-app

https://stackoverflow.com/questions/12013416/is-there-any-way-in-android-to-force-open-a-link-to-open-in-chrome

https://stackoverflow.com/questions/34491190/how-to-find-the-user-agent-string-for-linkedin-app-browser-from-ios

https://stackoverflow.com/questions/34359781/how-to-open-app-from-a-link-without-asking-user-to-decide-between-browser-or-app

https://android.stackexchange.com/questions/14869/the-name-of-the-default-android-browser