The URL.canParse() static method checks whether a URL can be parsed into a valid URL object. It's an alternative to calling new URL() in a try … catch statement.

The document.requestStorageAccess() method allows content in iframes to request storing and reading cookies and other site data, while the document.hasStorageAccess() method checks if such access is granted.

The rlh CSS length unit is a font-relative length relative to the line height of root element.

The navigator.userActivation API reveals whether the user has interacted with the page through an "activation" gesture such as a click, tap, or key press. User activation gated APIs (such as the fullscreen API) fail without user interaction, and this API allows you to predict such a failure.

The lh CSS length unit corresponds to the requested line height, the computed value of the line-height property. Some lines may be higher than this based on their content.

The fill-box, stroke-box, and view-box values for clip-path set an edge of the element's box to use as the clipping shape.

The :user-valid and :user-invalid pseudo-classes match form controls that have been marked as valid or invalid based on their validation constraints.

The getAuthenticatorData(), getPublicKey(), and getPublicKeyAlgorithm() methods of AuthenticatorAttestationResponse access credential data inside attestationObject without the need to parse it.

The isWellFormed() method of strings returns a boolean indicating if the string contains any Unicode lone surrogates. The toWellFormed() method returns a new string where all lone surrogates are replaced by the Unicode replacement character.

WAI-ARIA attributes have corresponding properties on Element and ElementInternals objects.

The <search> HTML element is a container that represents the parts of the web page with search functionality.

The hyphenate-character CSS property sets the character or string to use at the end of a line before a line break.

The overflow-block and overflow-inline CSS media queries set styles based on the way a device displays content that's larger than the viewport or page area. For example, a laptop lets users scroll to reveal content, while a printer displays overflowing content on additional pages.

The update CSS media query sets styles based on whether and how fast the user's device can modify display after it has been rendered. For example, you can avoid animations on devices that aren't fast enough to display them smoothly.

The @counter-style CSS at-rule sets custom counter styles for list items. For example, you can use a sequence of specific symbols instead of numbers for an ordered list.

The contain-intrinsic-size CSS property sets the intrinsic size of an element. When using size containment, the browser will lay out the element as if it had a single child of this size.

The DeviceMotion and DeviceOrientation events report the movement and orientation of the browser's device in physical space. Note that coordinates can differ noticeably between platforms and devices.

The hyphens CSS property controls when long words are broken by line wrapping. Although called hyphens, the property applies to word-splitting behavior across languages, such as customary spelling changes or the use of other characters. Support for non-English languages varies significantly.

The image-set() CSS function provides a set of images at different resolutions or pixel densities, which the browser can pick from, depending on the device capabilities.

The navigator.storage API provides information about the availability and persistence of the data that a site stores on the device, by using APIs such as the Cache API or the IndexedDB API.

The rel="modulepreload" attribute for the <link> HTML element indicates that a module script should be fetched, parsed, and compiled preemptively, and stored for later execution.

The subgrid value for the grid-template-columns and grid-template-rows properties allows a grid item to inherit the grid definition of its parent grid container.

The dirname attribute of <textarea> and <input> HTML elements includes the field's writing direction as form data on submission.

The display CSS property accepts multiple keyword values, such as inline flex or block flow, to explicitly set an element's inner and outer layout mode. Also known as 2-value, multi-keyword, or multiple value syntax.

The toReversed(), toSorted(), toSpliced(), and with() methods of arrays and typed arrays return changed copies of arrays. They stand in contrast to methods such as sort() or reverse() that change arrays in place.

The animation-composition CSS property chooses how to combine animations that affect the same property.

The Worker() constructor accepts { type: "module" } to load scripts that use import and export. Also known as ECMAScript modules or ESM in workers.

The window.print() method opens the browser's print dialog.

The e, pi, infinity, and NaN keywords represent well-defined constants accepted in CSS math functions such as calc().

The of syntax for the :nth-child() and :nth-last-child() CSS functional pseudo-classes match elements by the relative position of elements, counted from the first or last sibling matching a selector list.