Full-screen videos in a browser

isElementFullscreenEnabled on WebKit API

WKWebView playing a video on full-screen in landscape (app only supports portrait)

Starting on iOS 15.4 and macOS 12.3 WKPreferences has the new property isElementFullscreenEnabled, part of WKWebViewConfiguration, which enables JavaScript to make elements full-screen in a WKWebView, but it comes with some caveats.

macOS

On macOS is simple; set it true to play videos on full-screen and make any other HTML element full-screen via JavaScript.

myWebView.configuration.preferences.isElementFullscreenEnabled = true

iOS

On iOS, though, setting `isElementFullscreenEnabled = true` disables screen rotation while playing videos on full-screen for apps that only support Portrait Orientation.

This is important if you have an app that only supports portrait orientation but wants screen rotation when playing a video on full-screen (going back to portrait when the video finishes).

With isElementFullscreenEnabled = false, you can still play videos on full-screen (at least on YouTube), and rotate videos, but disables making other HTML elements full-screen.