EventTarget.addEventListener()

The modern standard API for adding DOM event handlers. Introduced in the DOM Level 2 Events spec. Also implies support for `removeEventListener`, the [capture phase](https://dom.spec.whatwg.org/#dom-event-capturing_phase) of DOM event dispatch, as well as the `stopPropagation()` and `preventDefault()` event methods.

selector list argument of :not()

Selectors Level 3 only allowed `:not()` pseudo-class to accept a single simple selector, which the element must not match any of. Thus, `:not(a, .b, [c])` or `:not(a.b[c])` did not work. Selectors Level 4 allows `:not()` to accept a list of selectors. Thus, `:not(a):not(.b):not([c])` can instead be written as `:not(a, .b, [c])` and `:not(a.b[c])` works as intended.

selector list argument of :nth-child and :nth-last-child CSS pseudo-classes

The newest versions of `:nth-child()` and `:nth-last-child()` accept an optional `of S` clause which filters the children to only those which match the selector list `S`. For example, `:nth-child(1 of .foo)` selects the first child among the children that have the `foo` class (ignoring any non-`foo` children which precede that child). Similar to `:nth-of-type`, but for arbitrary selectors instead of only type selectors.

Datalist element

Method of setting a list of options for a user to select in a text field, while leaving the ability to enter a custom value.

Reversed attribute of ordered lists

This attribute makes an ordered list number its items in descending order (large to small), instead of ascending order (small to large; the default). The order that the list items are displayed in is not affected.

"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.

Passive event listeners

Event listeners created with the `passive: true` option cannot cancel (`preventDefault()`) the events they receive. Primarily intended to be used with touch events and `wheel` events. Since they cannot prevent scrolls, passive event listeners allow the browser to perform optimizations that result in smoother scrolling.

counter api: liststyle

css property: list-style

css property: list-style-image

css property: list-style-image: none

css property: list-style-position

css property: list-style-type

css property: list-style-type: afar

css property: list-style-type: amharic

css property: list-style-type: armenian

css property: list-style-type: bengali

css property: list-style-type: binary

css property: list-style-type: circle

css property: list-style-type: decimal

css property: list-style-type: disc

css property: list-style-type: ethiopic

css property: list-style-type: georgian

css property: list-style-type: gujarati

css property: list-style-type: gurmukhi

css property: list-style-type: hangul

css property: list-style-type: hebrew

css property: list-style-type: hiragana

css property: list-style-type: kannada

css property: list-style-type: katakana

css property: list-style-type: khmer

css property: list-style-type: lao

css property: list-style-type: myanmar

css property: list-style-type: none

css property: list-style-type: octal

css property: list-style-type: oriya

css property: list-style-type: oromo

css property: list-style-type: persian

css property: list-style-type: sidama

css property: list-style-type: somali

css property: list-style-type: square

css property: list-style-type: symbols

css property: list-style-type: tamil

css property: list-style-type: telugu

css property: list-style-type: thai

css property: list-style-type: tibetan

css property: list-style-type: tigre

css property: list-style-type: urdu

css property: list-style: symbols

css selector: selector list (`,`)