What Is a Fullscreen Test?
This tool actually triggers your browser's real Fullscreen API to expand an element to fill your entire screen, removing all browser chrome, and confirms genuine support by tracking the actual fullscreen change events your browser fires when entering and exiting. It's a functional test - a real fullscreen session, not a simulated full-window view using CSS alone.
How to Use the Fullscreen Test
- Click "Enter Fullscreen" - your browser should expand the test box to fill your entire screen.
- Confirm all browser toolbars and tabs disappear, replaced by just the test content.
- Press Esc, or click inside the box, to exit fullscreen.
- Check "Change Events Fired" - it should increase by one each time you enter or exit.
How It Works
This tool calls requestFullscreen() (or the appropriate vendor-prefixed equivalent for
older browser support) on the test box element, which is the standard way web pages request genuine
fullscreen display. It then listens for the fullscreenchange event, which browsers fire every
time fullscreen state actually changes - whether triggered by this button, the Esc key, or any other method
- confirming the transition is real and being reported correctly by the browser.
Understanding Your Results
- Fullscreen activates cleanly with all browser chrome hidden - your browser fully supports the Fullscreen API and is behaving correctly.
- "Change Events Fired" increases correctly on both entry and exit - the event system this test (and any website using fullscreen video or presentations) relies on is functioning properly.
- "API Supported" shows "No" - an older or unusual browser lacking Fullscreen API support; this is uncommon in modern browsers but can appear in certain embedded webviews or restricted contexts.
- Fullscreen request fails with an error - some browsers require the request to originate from within a direct user interaction (like this button's click), and will reject requests made outside that context.
Browser Limitations
Fullscreen requests must generally be triggered by a direct user gesture like a click - browsers block
automatic fullscreen requests on page load as a protection against disorienting or deceptive full-screen
takeovers. Some embedded contexts, like certain iframes without the appropriate allow="fullscreen"
permission, can also block fullscreen requests entirely regardless of browser support.
Common Mistakes to Avoid
- Expecting fullscreen to trigger without a click - browsers require a genuine user gesture for security reasons; automatic requests are blocked.
- Testing inside a restricted iframe - some embedding contexts block fullscreen regardless of the browser's own support.
- Confusing a maximized browser window with true fullscreen - genuine fullscreen mode removes all browser UI entirely, which is a distinctly different state from simply maximizing the window.
Frequently Asked Questions
Why did fullscreen fail when I clicked the button?
Some browsers or embedding contexts, such as certain restricted iframes, block fullscreen requests entirely; check that you're viewing this test on its direct page rather than inside another embedded frame.
Is this the same as pressing F11 in my browser?
They achieve a similar visual result, but F11 is a browser-level keyboard shortcut controlled entirely by the browser itself, while this test uses the web-facing Fullscreen API that any website can request with your permission via a click.
Why do browsers require a click instead of allowing automatic fullscreen?
Allowing pages to enter fullscreen automatically could be used deceptively, for example to hide the real address bar and mimic a different website; requiring a genuine user gesture prevents that kind of abuse.
Is any data collected during this test?
No, this test only interacts with browser display APIs locally - nothing about your session is recorded or transmitted.
Does this work the same way on mobile browsers?
Most modern mobile browsers support the Fullscreen API similarly, though some have additional restrictions or slightly different visual behavior compared to desktop browsers.
Conclusion
A genuine fullscreen entry and exit, with correctly firing change events, confirms your browser handles this API the way many video players, presentation tools, and games depend on. For a broader check of your browser's other capabilities, see Browser Feature Detection.