The navigator.locks API coordinates work with shared resources through mutually exclusive ownership of a resource's name. Also known as web locks.

The Object.hasOwn() static method checks whether an object has a given property. It's a more robust alternative to the Object.prototype.hasOwnProperty() method.

The contain: paint CSS declaration prevents an element's descendants from being drawn outside the boundaries of the containing element, with any overflow clipped. This permits the browser to avoid slower painting calculations.

The contain: size CSS declaration sets an element's dimensions exclusively by its height and width properties, ignoring its contents and descendants. This permits the browser to avoid slower layout calculations.

The at() method of strings returns the character (one UTF-16 code unit) at an index, including negative indices for getting the character relative to the end of the string. Also known as the relative indexing method.

The appearance CSS property controls the appearance of form controls. Using appearance: none disables any default native appearance and allows the elements to be styled with CSS.

The contain CSS property sets limits to the scope of styles, layout, and paint rendering for speed and efficiency. The none keyword value disables containment, strict is equivalent to contain: size layout style paint, and content is equivalent to contain: layout style paint.

The navigator.hardwareConcurrency property is the number of logical processors available to run threads on the user's computer.

The scroll-behavior CSS property controls whether scrolling is smooth or snaps, for scroll actions not performed by the user such as those triggered by navigation.

The structuredClone() global method creates a deep copy of an object. Values that cannot be cloned can instead be transferred, making the original value no longer usable.

The text-combine-upright CSS property displays multiple characters in the space of a single character in vertical text. This is used in East Asian documents to display Latin-based strings such as components of a date or letters of an initialism.

The text-decoration-skip-ink CSS property sets whether underlines and overlines may be interrupted where the line would cross a glyph.

The text-emphasis CSS property sets position and style for text emphasis marks, especially for East Asian languages.

The color-scheme CSS property sets which color schemes (light or dark) an element uses and may prevent automatic dark mode adjustments by the browser.

The font-synthesis CSS shorthand property disables all font synthesis except the given kinds. To disable a specific kind of font synthesis, instead use the longhand properties such as font-synthesis-style and font-synthesis-weight.