IconVault's Screen Orientation Playground reads your real screen.orientation and mirrors it: the type (portrait-primary, landscape-secondary, and friends) and angle update live as you rotate your device, and an animated phone mock follows along. Buttons demo lock() for all eight orientation values and unlock(), with the genuine success or rejection shown, and a fullscreen toggle is included because most browsers only allow locking from fullscreen. It is free and runs fully in your browser.

Screen orientation matters for games, video, and kiosk apps, but the API contract has teeth: lock() returns a promise that rejects on desktop, on non-fullscreen pages, and where the platform forbids it. This lab reports those real outcomes instead of faking a lock, so you learn the exact conditions under which orientation locking works, and ships a copyable pattern with the try/catch you will need in production.