Arrow functions

Function shorthand using `=>` syntax and lexical `this` binding.

CSS background-repeat round and space

Allows CSS background images to be repeated without clipping.

CSS background-position edge offsets

Allows CSS background images to be positioned relative to the specified edge using the 3 to 4 value syntax. For example: `background-position: right 5px bottom 5px;` for positioning 5px from the bottom-right corner.

Media Queries: Range Syntax

Syntax improvements to make media queries using features that have a "range" type (like width or height) less verbose. Can be used with ordinary mathematical comparison operators: `>`, `<`, `>=`, or `<=`. For example: `@media (100px <= width <= 1900px)` is the equivalent of `@media (min-width: 100px) and (max-width: 1900px)`

CSS Relative color syntax

Relative color syntax in CSS allows a color to be defined relative to another color using the `from` keyword and optionally `calc()` for any of the color values.

CSS @when / @else conditional rules

Syntax allowing CSS conditions (like media and support queries) to be written more simply, as well as making it possible to write mutually exclusive rules using `@else` statements.

ES6 classes

ES6 classes are syntactical sugar to provide a much simpler and clearer syntax to create objects and deal with inheritance.

csspropertyrule api: syntax

css at-rule: `@media`: `or` syntax from media queries level 4

css at-rule: `@property`: `syntax` descriptor

css property: background-repeat: two-value syntax (different values for x & y directions)

css property: cursor: `url()` positioning syntax

css property: font-size-adjust: two-value syntax

css property: font-stretch: `<percentage>` syntax

css property: font-weight: `<number>` syntax

css property: overflow: multiple keyword syntax for `overflow-x` and `overflow-y`

css property: text-overflow: two-value syntax

css property: transform-origin: three-value syntax

css selector: `:nth-last-child()`: `of <selector>` syntax

types: `<color>`: `color()` (profiled color values): relative `color()` syntax

types: `<color>`: `hsl()` (hsl color model): relative hsl colors

types: `<color>`: `hwb()` (hwb color model): relative hwb colors

types: `<color>`: `lab()` (lab color model): relative lab colors

types: `<color>`: `lch()` (lch color model): relative lch colors

types: `<color>`: `oklab()` (oklab color model): relative oklab colors

types: `<color>`: `oklch()` (oklch color model): relative oklch colors

types: `<color>`: `rgb()` (rgb color model): relative rgb colors

types: `<gradient>`: `radial-gradient()`: `at` syntax

types: `<gradient>`: `repeating-radial-gradient()`: `at` syntax

types: `<position>`: four-value syntax for offset from any edge

types: `<position>`: syntax combining a keyword and `<length>` or `<percentage>`

javascript built-in: syntaxerror

javascript built-in: syntaxerror: `syntaxerror` is serializable

javascript built-in: syntaxerror: `syntaxerror()` constructor

grammar: hashbang (`#!`) comment syntax

javascript operator: spread syntax (...)

javascript operator: spread syntax (...): spread in array literals

javascript operator: spread syntax (...): spread in function calls

javascript operator: spread syntax (...): spread in object literals

javascript statement: import: import attributes with `assert` syntax (formerly import assertions)

javascript statement: import: import attributes with `assert` syntax (formerly import assertions): `assert {type: 'css'}`

javascript statement: import: import attributes with `assert` syntax (formerly import assertions): `assert {type: 'json'}`

javascript statement: import: import attributes (`with` syntax)

javascript statement: import: import attributes (`with` syntax): `with {type: 'css'}`

javascript statement: import: import attributes (`with` syntax): `with {type: 'json'}`

ecmascript 2023 (es14)

empty tag syntax: <>