📃 October 2018 release notes

Newly available

The following features are newly available:

<output>: The <output> element represents the result of a calculation, user action, or form entry.
overflow-wrap: The overflow-wrap CSS property breaks a line of text onto multiple lines inside the targeted element in an otherwise unbreakable place to prevent overflow. The legacy property is word-wrap.
Promise finally(): The promise finally() method executes a function when the promise settles (resolves or rejects).
resolution media query (compatibility prefixes): The -webkit-device-pixel-ratio, -webkit-min-device-pixel-ratio, and -webkit-max-device-pixel-ratio CSS media queries are standardized compatibility alternatives to resolution media queries.
tabindex: The tabindex HTML attribute make an element focusable, and sets the element's relative ordering for sequential focus navigation.

The following features are now available in Chrome:

Payment handler: 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.
Stable array sort: Stable array sort() function
Web Bluetooth: The Web Bluetooth API enables selecting and communicating with nearby Bluetooth devices.

The following features are now available in Chrome Android:

Payment handler: 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.
Stable array sort: Stable array sort() function
Web authentication: The web authentication API allows you to create public key-based credentials and use them for authentication, such as when signing in. Also known as WebAuthn.

The following features are now available in Edge:

Constraint validation API: Methods that validate form controls before submission, such as checkValidity(), reportValidity() and setCustomValidity().
download: The download attribute for <a> elements loads the target URL as a file to be saved, instead of navigating to it. An optional attribute value sets a default file name.
Intl.PluralRules: The Intl.PluralRules API creates a locale-aware object that tells you which of the language's pluralization rules apply based on a given number.
overscroll-behavior: The overscroll-behavior CSS property disables default scrolling behaviors when the edges of a scrolling area are reached.
Non-trapping float-to-int conversion (WebAssembly): Saturating floating-point to integer conversion operators return the maximum or minimum integer value on overflow instead of trapping.
Sign extension operators (WebAssembly): Sign-extension operator instructions extend the width of 8-bit, 16-bit, and 32-bit values to 32-bit and 64-bit values.
Web authentication: The web authentication API allows you to create public key-based credentials and use them for authentication, such as when signing in. Also known as WebAuthn.
WebP: The WebP image format is a raster graphics file format that supports animation, alpha transparency, and lossy as well as lossless compression.

The following features are now available in Firefox:

Autonomous custom elements: Autonomous custom elements are HTML elements with a hyphenated tag name (like <example-element>) that have behaviors you define.
Clearing site data: The Clear-Site-Data header deletes browsing data (such as cookies, storage, or cache) associated with the requesting website.
Customized built-in elements: Customized built-in elements are HTML elements that extend built-in elements using the is attribute, to add new behaviors that you define.
Flexbox gap: The gap CSS property in a flexbox layout sets the size of the space between items.
Host: The :host CSS pseudo-class selects the containing element of the shadow tree in which it is used. The :host() CSS pseudo-class selects the that element only if it matches the provided selector.
prefers-reduced-motion media query: The prefers-reduced-motion CSS media query sets styles based on whether the user prefers to minimize the amount of non-essential animations on the device, such as scrolling, panning, zooming, and strobing.
Shadow DOM: Shadow DOM allows you to attach encapsulated "shadow" DOM trees to elements. A shadow DOM tree is a separate component, isolated from the scripts and styles in other parts of the document. This is a part of Web Components.
<slot>: The <slot> HTML element is a placeholder inside a web component where consumers of the component can insert their own markup.

The following features are now available in Firefox for Android:

Autonomous custom elements: Autonomous custom elements are HTML elements with a hyphenated tag name (like <example-element>) that have behaviors you define.
Clearing site data: The Clear-Site-Data header deletes browsing data (such as cookies, storage, or cache) associated with the requesting website.
Customized built-in elements: Customized built-in elements are HTML elements that extend built-in elements using the is attribute, to add new behaviors that you define.
Flexbox gap: The gap CSS property in a flexbox layout sets the size of the space between items.
Host: The :host CSS pseudo-class selects the containing element of the shadow tree in which it is used. The :host() CSS pseudo-class selects the that element only if it matches the provided selector.
Shadow DOM: Shadow DOM allows you to attach encapsulated "shadow" DOM trees to elements. A shadow DOM tree is a separate component, isolated from the scripts and styles in other parts of the document. This is a part of Web Components.
<slot>: The <slot> HTML element is a placeholder inside a web component where consumers of the component can insert their own markup.