Feature-Policy: sync-xhr

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

Non-standard: This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The HTTP Feature-Policy header sync-xhr directive controls whether the current document is allowed to make synchronous XMLHttpRequest requests.


Feature-Policy: sync-xhr <allowlist>;

A list of origins for which the feature is allowed. See Feature-Policy.

Default policy

By default the policy is set to *, which means synchronous requests are allowed in all frames.

Browser compatibility

BCD tables only load in the browser

See also