FeaturePolicy.allowsFeature() - Web APIs 编辑

Experimental

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

The allowsFeature() method of the FeaturePolicy interface enables introspection of individual directives of the Feature 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).

Syntax

const allowed = FeaturePolicy.allowsFeature(<feature>)

or

const allowed = FeaturePolicy.allowsFeature(<feature>, <origin>)

Parameters

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.

Return value

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

Example

The following example queries whether or not the document is allowed to use camera API by the Feature 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.")
}

Specifications

Browser compatibility

BCD tables only load in the browser