files/en-us/web/http/reference/headers/permissions-policy/fullscreen/index.md
{{SeeCompatTable}}
The HTTP {{HTTPHeader("Permissions-Policy")}} header fullscreen directive controls whether the current document is allowed to use {{domxref('Element.requestFullscreen()')}}.
Specifically, where a defined policy blocks use of this feature, {{domxref('Element.requestFullscreen', "requestFullscreen()")}} calls will return a {{jsxref('Promise')}} that rejects with a {{jsxref('TypeError')}}.
[!NOTE] If both this directive (i.e., via the
allowattribute) and theallowfullscreenattribute are present on an<iframe>element, this directive takes precedence.
Permissions-Policy: fullscreen=<allowlist>;
<allowlist>
Permissions-Policy > Syntax for more details.The default allowlist for fullscreen is self. The top-level browsing context and same-origin iframes are allowed access to the fullscreen feature by default.
SecureCorp Inc. wants to disallow fullscreen within all cross-origin iframes except those whose origin is https://example.com. It can do so by delivering the following HTTP response header to define a Permissions Policy:
Permissions-Policy: fullscreen=(self "https://example.com")
SecureCorp Inc. must also include an {{HTMLElement('iframe','allow','#Attributes')}} attribute on each <iframe> element where fullscreen is to be allowed:
<iframe src="https://example.com/presentation" allow="fullscreen"></iframe>
[!NOTE] Specifying the
Permissions-Policyheader in this manner disallowsfullscreenfor other origins, even if they are allowed by the<iframe>allowattribute.
If an allowlist for fullscreen is not defined by a Permissions-Policy response header, user agents will apply the default allowlist self. In this mode, fullscreen is automatically allowed in the top-level browsing context and same-origin iframes, but not in cross-origin iframes.
To allow fullscreen in a cross-origin iframe, include an {{HTMLElement('iframe','allow','#Attributes')}} attribute on the <iframe> element:
<iframe src="https://other.com/videoplayer" allow="fullscreen"></iframe>
{{Specifications}}
{{Compat}}