30:T478,> *A powerful feature is a web platform feature (usually an API) for which a user gives express permission before the feature can be used.* > [Permissions Policy, 3.3 Powerful Features](https://www.w3.org/TR/permissions/#powerful-features) > *A policy-controlled feature is an API or behaviour which can be enabled or disabled in a document by referring to it in a permissions policy.* > [Permissions Policy, 4.1 Policy-controlled Features](https://www.w3.org/TR/permissions-policy-1/#features) This notebook explores access levels to various web APIs and some potential workarounds. ### Permission helper The notebook provides a helper to run code (and return its result) in a top-level window within the sandbox origin where access to certain features (e.g. screen capture) can be requested. Import the proxy window helper: ```js import {request} from "@mootari/powerful-features" ``` Take a look at the [importing notebooks](https://observablehq.com/@mootari/powerful-features/importers) or the sections below for examples. 31:T973, --- References: - https://www.w3.org/TR/permissions/#powerful-features - https://w3c.github.io/permissions-registry/ - https://developer.mozilla.org/en-US/docs/Web/API/Permissions/query - https://developer.mozilla.org/en-US/docs/Glossary/Transient_activation - https://developer.mozilla.org/en-US/docs/Web/API/Permissions_API APIs: - [Contact Picker API](https://developer.mozilla.org/en-US/docs/Web/API/Contact_Picker_API) - [Credential Management API](https://developer.mozilla.org/en-US/docs/Web/API/Credential_Management_API) - [File and Directory Entries API](https://developer.mozilla.org/en-US/docs/Web/API/File_and_Directory_Entries_API) - [File System Access API](https://developer.mozilla.org/en-US/docs/Web/API/File_System_Access_API) - [Gamepad API](https://developer.mozilla.org/en-US/docs/Web/API/Gamepad_API) - [Payment Request API](https://developer.mozilla.org/en-US/docs/Web/API/Payment_Request_API) - [Presentation API](https://developer.mozilla.org/en-US/docs/Web/API/Presentation_API) - [Screen Capture API](https://developer.mozilla.org/en-US/docs/Web/API/Screen_Capture_API/Using_Screen_Capture) / navigator.mediaDevices.getDisplayMedia - [Screen Wake Lock API](https://developer.mozilla.org/en-US/docs/Web/API/Screen_Wake_Lock_API) - [Web Audio API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Audio_API) - [Web Serial API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Serial_API) - [Web Share API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Share_API) - [WebHID API](https://developer.mozilla.org/en-US/docs/Web/API/WebHID_API) --- Other: - [EventSource](https://developer.mozilla.org/en-US/docs/Web/API/EventSource) - [Streams API](https://developer.mozilla.org/en-US/docs/Web/API/Streams_API) - [Vibration API](https://developer.mozilla.org/en-US/docs/Web/API/Vibration_API) - [Web Speech API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Speech_API) - [WebXR Device API](https://developer.mozilla.org/en-US/docs/Web/API/WebXR_Device_API) - document.pictureInPictureEnabled / https://developers.google.com/web/updates/2016/10/capture-stream - [Battery Status API](https://developer.mozilla.org/en-US/docs/Web/API/Battery_Status_API) Unrestricted / useful - [Page Visibility API](https://developer.mozilla.org/en-US/docs/Web/API/Page_Visibility_API) - [Network Information API](https://developer.mozilla.org/en-US/docs/Web/API/Network_Information_API) 32:T687,// See also https://chromium.googlesource.com/chromium/src/+/refs/heads/main/components/permissions_strings.grdp permissionNames = ({ "ambient-light-sensor": "https://developer.mozilla.org/en-US/docs/Web/API/AmbientLightSensor", "accelerometer": "https://developer.mozilla.org/en-US/docs/Web/API/Accelerometer", "accessibility-events": null, "background-sync": "https://developer.mozilla.org/en-US/docs/Web/API/Background_Synchronization_API", "camera": "https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/getUserMedia", "clipboard-read": "https://developer.mozilla.org/en-US/docs/Web/API/Clipboard/read", "clipboard-write": "https://developer.mozilla.org/en-US/docs/Web/API/Clipboard/write", "display-capture": "https://developer.mozilla.org/en-US/docs/Web/API/Screen_Capture_API", "geolocation": "https://developer.mozilla.org/en-US/docs/Web/API/Geolocation_API", "gyroscope": "https://developer.mozilla.org/en-US/docs/Web/API/Gyroscope", "magnetometer": "https://developer.mozilla.org/en-US/docs/Web/API/Magnetometer", "microphone": "https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/getUserMedia", "midi": "https://developer.mozilla.org/en-US/docs/Web/API/Web_MIDI_API", "notifications": "https://developer.mozilla.org/en-US/docs/Web/API/Notifications_API", "payment-handler": "https://developer.mozilla.org/en-US/docs/Web/API/Payment_Request_API", "persistent-storage": "https://developer.mozilla.org/en-US/docs/Web/API/StorageManager/persist", //"serial": "https://developer.mozilla.org/en-US/docs/Web/API/Web_Serial_API", "web-share": "https://developer.mozilla.org/en-US/docs/Web/API/Navigator/share", })33:T988,function request(onTrigger, { // Button label label = "Request permission", // Programmatically click the button auto = true, // Open a small popup instead of a new tab. Also accepts a windowFeatures string. popup = true, // Automatically close the window on invalidation invalidation: invalidated = invalidation, } = {}) { let value; const mainButtonOpen = html`