1. Case-insensitive CSS attribute selectors

    Including an `i` before the `]` in a CSS attribute selector causes the attribute value to be matched in an ASCII-case-insensitive manner. For example, `[b="xyz" i]` would match both `<a b="xyz">` and `<a b="XYZ">`.

  2. CSS display: contents

    `display: contents` causes an element's children to appear as if they were direct children of the element's parent, ignoring the element itself. This can be useful when a wrapper element should be ignored when using CSS grid or similar layout techniques.

  3. CSS font-stretch

    If a font has multiple types of variations based on the width of characters, this property allows the appropriate one to be selected. The property in itself does not cause the browser to stretch to a font. Note that `font-stretch` is an alias of the [`font-width`](/wf-font-width) CSS property.

  4. navigator.hardwareConcurrency

    Returns the number of logical cores of the user's CPU. The value may be reduced to prevent device fingerprinting or because it exceeds the allowed number of simultaneous web workers.

  5. HEIF/HEIC image format

    A modern image format based on the [HEVC video format](/hevc). HEIC generally has better compression than [WebP](/webp), JPEG, PNG and GIF. It is hard for browsers to support HEIC because it is [complex and expensive to license](https://en.wikipedia.org/wiki/High_Efficiency_Video_Coding#Patent_licensing). [AVIF](/avif) and [JPEG XL](/jpegxl) provide free licenses and are designed to supersede HEIC.

  6. HEVC/H.265 video format

    The High Efficiency Video Coding (HEVC) compression standard is a video compression format intended to succeed H.264. It is hard for browsers to universally support HEVC because it is [complex and expensive to license](https://en.wikipedia.org/wiki/High_Efficiency_Video_Coding#Patent_licensing). HEVC competes with [AV1](/av1) which has similar compression quality and provides a free license.

  7. "once" event listener option

    Causes an event listener to be automatically removed after it gets invoked, so that it only gets invoked once. Similar to jQuery's `$.one()` feature.

  8. rtcerror api: sctpcausecode

  9. javascript built-in: error: cause

  10. javascript built-in: error: `error()` constructor: `options.cause` parameter

  11. ecmascript 2022 (es13)