The Feature-Policy response header sets whether a policy-controlled feature, such as an API, may be used in a document. Not to be confused with permissions policy.

The beforeinstallprompt event fires when a Progressive Web App (PWA) is installable. You can cancel the event and later call event.prompt() to control when the installation prompt is shown. The appinstalled event fires when the PWA is successfully installed.

The clip CSS property sets the visible area of an absolutely positioned element.

The text-decoration: blink CSS declaration flashes text between visible and invisible.

The requestIdleCallback() API queues a function that runs in idle browser time, either at the end of a frame or when the user is inactive. Also known as the background tasks API.

The :past and :future CSS pseudo-classes match prior or upcoming text track cues during media playback.

The page lifecycle API helps you safely handle page suspensions or discards from memory. The freeze and resume events fire when the browser suspends or resumes a page from memory while the document.wasDiscarded property reports whether the page was reloaded after being dropped.

The navigator.vibrate() method makes a tactile alert, if the device is equipped with a haptic motor.

Browsers send the Save-Data HTTP request header when the user turns on a data-saving mode. It is a hint to reduce data sent to the browser. Servers should respond with alternative content, such as smaller images and videos, or different markup and styling.

The payment handler API registers a web application as a payment handler and responds to payment requests in the browser's user interface, rather than redirecting users to a separate site to complete a payment.

The navigator.registerProtocolHandler() method declares a site's ability to handle an address scheme (also known as a protocol). For example, an email site can register to open mailto: URLs or a VoIP site to open tel: URLs.

The alignment-baseline CSS property sets which baseline of an element is aligned with the corresponding baseline of its parent.

The text-size-adjust CSS property disables or modifies the browser's default text size adjustment for small screen sizes.

The :host-context() CSS pseudo-class selects the containing element of the shadow tree in which it is used if that element or an ancestor matches the provided selector.

The gamepad attribute of an XRInputSource represents an XR input device, such as a motion controller, that reports data from physical inputs (such as buttons, touch pads, and triggers).

The navigator.xr API represents the browser's virtual reality or augmented reality system. You can use to request a WebXR session.

The navigator.getBattery() API obtains information about the device's battery, including charge level and status. Also known as the Battery API.

The FederatedCredential API represents the details required to authenticate a user using a third-party identity provider. Not to be confused with federated credential management (FedCM).

The PasswordCredential API represents a username and password.

The optional alpha parameter of a 2D canvas's getContext() method sets whether the canvas has an alpha transparency channel. If set to false, then this permits the browser to optimize compositing for an opaque canvas.

The resize CSS property sets whether an element can be resized by the user, and on which axes.

The background synchronization API registers a service worker callback to run only when the device is no longer offline. You can use this to let users continue using your app while offline and synchronize with a server after reconnecting.

The navigator.keyboard.lock() API allows you to capture keys that are normally reserved by the operating system. It can be used to provide an immersive fullscreen experience such as games.

The navigator.keyboard.getLayoutMap() API returns a map from key codes to human readable key names. It can be used to describe buttons to the user when using the keyboard as a set of buttons, such as in games.

The Gyroscope API reads the angular velocity of a device in three dimensions.

The AbsoluteOrientationSensor and RelativeOrientationSensor APIs describe the physical orientation of a device in three-dimensional space, either in relation to the Earth's coordinate system or in relation to the device's own orientation, respectively.

The controlslist attribute for <audio> or <video> hides parts of the browser's built-in controls. For example, controlslist="nofullscreen" removes the button to play the video in fullscreen.

The paint() CSS function creates a custom image, drawn using a paint worklet, for an element's background or border.

Customized built-in elements are HTML elements that extend built-in elements using the is attribute, to add new behaviors that you define.

Background fetch downloads data in the background even when the web page is closed.