The allowsFeature() method of the FeaturePolicy interface enables introspection of individual directives of the Permissions Policy it is run on. It returns a Boolean that is true if and only if the specified feature is allowed in the specified context (or the default context if no context is specified).

const allowed = FeaturePolicy.allowsFeature(feature)

or

const allowed = FeaturePolicy.allowsFeature(feature, origin);

Feature name

A specific feature name must be specified.

Origin name Optional

An origin URL to check the feature on. If it is omitted the default origin is used.

A Boolean that is true if and only if the feature is allowed.

The following example queries whether or not the document is allowed to use camera API by the Permissions Policy. Please note that Camera API might be restricted by the Permissions API, if the user did not grant the corresponding permission yet.

// First, get the Feature Policy object
const featurePolicy = document.featurePolicy;

// Then query feature for specific
const allowed = featurePolicy.allowsFeature("camera");

if (allowed) {
  console.log("FP allows camera.");
} else {
  console.log("FP does not allows camera.");
}