Detect if web page is loaded within native Facebook app on iOS / Android

Question

I have a web app using the Facebook javascript SDK. I want to detect if this web app is running within the native Facebook app on iOS or Android. The reason is because if not running within a proper browser I want to open certain links in a floating iframe instead of a new web page/tab.

How can I easily detect if running on mobile within the native Facebook app. I am aware of the answer that suggests using FB.UA but that answer is 3 years old and that API is not documented anymore.

OR

Is it possible specify an HREF to launch a URL in the native browser on a mobile device? Then my links could launch a browser and my web app keeps running within the Facebook native app.

Answer 1

This works fine for me in JavaScript:

if (navigator.userAgent.match(/(iPod|iPhone|iPad)/) && navigator.userAgent.match(/FBAV/i)) {
    //iOS Facebook App Browser detected
}