1. ChildNode.remove()

    DOM node method to remove the node itself from the document.

  2. Credential Management API

    API that provides a programmatic interface to the browser's credential manager. In short, an origin can request a user's credentials to sign them in, or can ask the browser to save credentials on the user's behalf. Both of these requests are user-mediated.

  3. CSS element() function

    This function renders a live image generated from an arbitrary HTML element

  4. CSS Filter Effects

    Method of applying filter effects using the `filter` property to elements, matching filters available in SVG. Filter functions include blur, brightness, contrast, drop-shadow, grayscale, hue-rotate, invert, opacity, sepia and saturate.

  5. ::first-letter CSS pseudo-element selector

    CSS pseudo-element that allows styling only the first "letter" of text within an element. Useful for implementing initial caps or drop caps styling.

  6. Custom Elements (deprecated V0 spec)

    Original V0 version of the custom elements specification. See [Custom Elements V1](#feat=custom-elementsv1) for support for the latest version.

  7. Custom Elements (V1)

    One of the key features of the Web Components system, custom elements allow new HTML tags to be defined.

  8. Dialog element

    Method of easily creating custom dialog boxes to display to the user with modal or non-modal options. Also includes a `::backdrop` pseudo-element for behind the element.

  9. document.scrollingElement

    `document.scrollingElement` refers to the element that scrolls the document.

  10. Element.closest()

    DOM method that returns the current element if it matches the given selector, or else the closest ancestor element that matches the given selector, or else null.

  11. document.elementFromPoint()

    Given coordinates for a point relative to the viewport, returns the element that a click event would be dispatched at if the user were to click the point (in other words, the element that hit-testing would find).

  12. Scroll methods on elements (scroll, scrollTo, scrollBy)

    Methods to change the scroll position of an element. Similar to setting `scrollTop` & `scrollLeft` properties, but also allows options to be passed to define the scroll behavior.

  13. Encrypted Media Extensions

    The EncryptedMediaExtenstions API provides interfaces for controlling the playback of content which is subject to a DRM scheme.

  14. EOT - Embedded OpenType fonts

    Type of font that can be derived from a regular font, allowing small files and legal use of high-quality fonts. Usage is restricted by the file being tied to the website

  15. Filesystem & FileWriter API

    Method of reading and writing files to a sandboxed file system.

  16. getElementsByClassName

    Method of accessing DOM elements by class name

  17. HTML5 semantic elements

    HTML5 offers some new elements, primarily for semantic purposes. The elements include: `section`, `article`, `aside`, `header`, `footer`, `nav`, `figure`, `figcaption`, `time`, `mark` & `main`.

  18. HTMLElement.innerText

    A property representing the text within a DOM element and its descendants. As a getter, it approximates the text the user would get if they highlighted the contents of the element with the cursor and then copied to the clipboard.

  19. Email, telephone & URL input types

    Text input fields intended for email addresses, telephone numbers or URLs. Particularly useful in combination with [form validation](https://caniuse.com/#feat=form-validation)

  20. Element.insertAdjacentElement() & Element.insertAdjacentText()

    Methods for inserting an element or text before or after a given element, or appending or prepending an element or text to a given element's list of children.

  21. Element.insertAdjacentHTML()

    Inserts a string of HTML into a specified position in the DOM relative to the given element.

  22. Media Capture from DOM Elements API

    API to capture Real-Time video and audio from a DOM element, such as a `<video>`, `<audio>`, or `<canvas>` element via the `captureStream` method, in the form of a `MediaStream`

  23. Context menu item (menuitem element)

    Method of defining a context menu item, now deprecated and [removed from the HTML specification](https://github.com/whatwg/html/issues/2730).

  24. theme-color Meta Tag

    Meta tag to define a suggested color that browsers should use to customize the display of the page or of the surrounding user interface. The meta tag overrides any theme-color set in the web app manifest.

  25. File System Access API

    API for manipulating files in the device's local file system (not in a sandbox).

  26. prefers-color-scheme media query

    Media query to detect if the user has set their system to use a light or dark color theme.

  27. rem (root em) units

    Type of unit similar to `em`, but relative only to the root element, not any parent element. Thus compounding does not occur as it does with `em` units.

  28. HTML templates

    Method of declaring a portion of reusable markup that is parsed but not rendered until cloned.

  29. ES6 Template Literals (Template Strings)

    Template literals are string literals allowing embedded expressions using backtick characters (`). You can use multi-line strings and string interpolation features with them. Formerly known as template strings.

  30. Temporal

    A modern API for working with date and time, meant to supersede the original `Date` API.

  31. text-emphasis styling

    Method of using small symbols next to each glyph to emphasize a run of text, commonly used in East Asian languages. The `text-emphasis` shorthand, and its `text-emphasis-style` and `text-emphasis-color` longhands, can be used to apply marks to the text. The `text-emphasis-position` property, which inherits separately, allows setting the emphasis marks' position with respect to the text.

  32. Video element

    Method of playing videos on webpages (without requiring a plug-in). Includes support for the following media properties: `currentSrc`, `currentTime`, `paused`, `playbackRate`, `buffered`, `duration`, `played`, `seekable`, `ended`, `autoplay`, `loop`, `controls`, `volume` & `muted`

  33. WebAssembly

    WebAssembly or "wasm" is a new portable, size- and load-time-efficient format suitable for compilation to the web.

  34. wbr (word break opportunity) element

    Represents an extra place where a line of text may optionally be broken.

  35. css api: em

  36. document api: embeds

  37. speechrecognitionevent api: emma

  38. textmetrics api: emheightascent

  39. textmetrics api: emheightdescent

  40. trustedtypepolicyfactory api: emptyhtml

  41. trustedtypepolicyfactory api: emptyscript

  42. xrpose api: emulatedposition

  43. css property: empty-cells

  44. css property: text-emphasis-color

  45. css selector: `:empty`

  46. html element: em

  47. html element: embed

  48. javascript built-in: regexp: source: "(?:)" for empty regexps

  49. emoji support

  50. empty tag syntax: <>