Feature-Policy: fullscreen

Experimental

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The HTTP Feature-Policy header fullscreen directive controls whether the current document is allowed to use Element.requestFullScreen(). When this policy is enabled, the returned Promise rejects with a TypeError.

By default, top-level documents and their same-origin child frames can request and enter fullscreen mode. This directive allows or prevents cross-origin frames from using fullscreen mode. This includes same-origin frames.

If both this directive (i.e. via the allow attribute) and the allowfullscreen attribute are present on an <iframe> element, this directive takes precedence. There was a bug whereby the fullscreen directive didn't work unless the allowfullscreen attribute was also present, but this has been fixed as of Firefox 80 (bug 1608358).

Syntax

Feature-Policy: fullscreen <allowlist>;
<allowlist>

An allowlist is a list of origins that takes one or more of the following values, separated by spaces:

  • *: The feature will be allowed in this document, and all nested browsing contexts (iframes) regardless of their origin.
  • 'self': The feature will be allowed in this document, and in all nested browsing contexts (iframes) in the same origin.
  • 'src': (In an iframe allow attribute only) The feature will be allowed in this iframe, as long as the document loaded into it comes from the same origin as the URL in the iframe's src attribute.
    The 'src' origin is used in the iframe allow attribute only, and is the default allowlist value. 
  • 'none': The feature is disabled in top-level and nested browsing contexts.
  • <origin(s)>: The feature is allowed for specific origins (for example, https://example.com). Origins should be separated by a space.

The values * (enable for all origins) or 'none' (disable for all origins) may only be used alone, while 'self' and 'src' may be used with one or more origins.

Features are each defined to have a default allowlist, which is one of:

  • *: The feature is allowed by default in top-level browsing contexts and all nested browsing contexts (iframes).
  • 'self': The feature is allowed by default in top-level browsing contexts and in nested browsing contexts (iframes) in the same origin. The feature is not allowed in cross-origin documents in nested browsing contexts.
  • 'none': The feature is disabled in top-level and nested browsing contexts.

Default policy

The default value is 'self'.

Examples

General example

SecureCorp Inc. wants to disable the Fullscreen API within all browsing contexts except for its own origin and those whose origin is https://example.com. It can do so by delivering the following HTTP response header to define a feature policy:

Feature-Policy: fullscreen 'self' https://example.com

With an <iframe> element

FastCorp Inc. wants to disable fullscreen for all cross-origin child frames, except for a specific <iframe>. It can do so by delivering the following HTTP response header to define a feature policy:

Feature-Policy: fullscreen 'self'

Then include an allow attribute on the <iframe> element:

<iframe src="https://other.com/videoplayer" allow="fullscreen"></iframe>

iframe attributes can selectively enable features in certain frames, and not in others, even if those frames contain documents from the same origin.

Specifications

Specification Status Comment
Permissions Policy Editor's Draft Initial definition.
Fullscreen API
The definition of 'Fullscreen' in that specification.
Editor's Draft Defines the fullscreen policy.

Browser compatibility

BCD tables only load in the browser

See also