Feature Policy allows web developers to selectively enable, disable, and modify the behavior of various features and APIs in the browser. This can provide a well-lit path towards good performance and prevent common footguns when building and maintaining web apps.

Feature policy is not supported in your browser. Try Chrome Canary and enable the --enable-experimental-web-platform-features flag.

You control feature policies through an HTTP header:

Feature-Policy: geolocation *
Feature-Policy: geolocation 'none'
Feature-Policy: geolocation 'self'
Feature-Policy: geolocation https://google-developers.appspot.com

or by adding the allow attribute on iframes:

<iframe allow="geolocation">
<iframe allow="geolocation 'self'">
<iframe allow="geolocation 'none'">
<iframe allow="geolocation https://google-developers.appspot.com">