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[Web API type definition issue] Element.requestFullscreen should be optional #2211
Description
Summary
typeof document.documentElement.requestFullscreen is undefined in iOS Safari
Expected vs. Actual Behavior
typeof document.documentElement.requestFullscreen
Expected: not defined in iOS 26.0.1 Safari (and probably in the webview)
Actual: always a function
Playground Link
No response
Browser Support
- This API is supported in at least two major browser engines (not two Chromium-based browsers).
Have Tried The Latest Releases
- This issue applies to the latest release of TypeScript.
- This issue applies to the latest release of
@types/web.
Additional Context
Suggested change will enforce optional chaining for safer runtime code.
document.documentElement.requestFullscreen?.()
Activity
jakebailey commentedon Oct 29, 2025
It's only undefined because Safari doesn't implement it yet: https://developer.mozilla.org/en-US/docs/Web/API/Element/requestFullscreen
We don't generally make everything potentially undefined because one browser is lagging behind. If two engines have the feature, then we include the type.
hyunbinseo commentedon Oct 29, 2025
I do understand that iOS Safari is the only one lagging behind, but is Apple even willing to implement it?
I would love to know a way to config it as optional — I wasn't doing QA with iPhones, and I've had to fix mistakes in bulk with a string search.
saschanaz commentedon Nov 5, 2025
What version of iOS Safari are we talking about? Per the WebKit IDL it should be available everywhere. 🤔
hyunbinseo commentedon Nov 5, 2025
Kagami Sascha Rosylight (@saschanaz) all versions of iOS Safari including the latest 26.
Personal test results:
https://caniuse.com/fullscreen
https://github.com/mdn/browser-compat-data/blob/88673dfeb94aa588d96baf90dbc8742538d78d12/api/Element.json#L4805-L4813
saschanaz commentedon Nov 5, 2025
The source of truth is the WebKit source code, everything else is an observed result. 🤔
saschanaz commentedon Nov 5, 2025
I guess iOS doesn't have webkitRequestFullScreen either?
saschanaz commentedon Nov 5, 2025
fwiw, you can use https://mdn-bcd-collector.gooborg.com/ (the same thing that MDN uses to gather the data)
hyunbinseo commentedon Nov 8, 2025
These are the tests I've ran. Is there a webkit prefixed version that I am supposed to run?