1. Blob URLs

    Method of creating URL handles to the specified File or Blob object.

  2. 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.

  3. :in-range and :out-of-range CSS pseudo-classes

    If a temporal or number `<input>` has `max` and/or `min` attributes, then `:in-range` matches when the value is within the specified range and `:out-of-range` matches when the value is outside the specified range. If there are no range constraints, then neither pseudo-class matches.

  4. CSS revert value

    A CSS keyword value that resets a property's value to the default specified by the browser in its UA stylesheet, as if the webpage had not included any CSS. For example, `display:revert` on a `<div>` would result in `display:block`. This is in contrast to the `initial` value, which is simply defined on a per-property basis, and for `display` would be `inline`.

  5. CSS text-box-trim & text-box-edge

    Provides the ability to remove the vertical space appearing above and below text glyphs, allowing more precise positioning and alignment. Previously specified as the `leading-trim` & `text-edge` properties.

  6. Date.prototype.toLocaleDateString

    Date method to generate a language sensitive representation of a given date, formatted based on a specified locale and options.

  7. Attributes for form submission

    Attributes for form submission that may be specified on submit buttons. The attributes are: `formaction`, `formenctype`, `formmethod`, `formnovalidate`, and `formtarget`

  8. srcdoc attribute for iframes

    Override the content specified in the `src` attribute (if present) with HTML content within the attribute.

  9. Element.insertAdjacentHTML()

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

  10. Intrinsic & Extrinsic Sizing

    Allows for the heights and widths to be specified in intrinsic values using the `max-content`, `min-content`, `fit-content` and `stretch` (formerly `fill`) properties.

  11. Resource Hints: prerender

    Gives a hint to the browser to render the specified page in the background, speeding up page load if the user navigates to it. This is indicated using `<link rel="prerender" href="(url)">`

  12. Promise.prototype.finally

    When the promise is settled, whether fulfilled or rejected, the specified callback function is executed.

  13. HTTP Public Key Pinning

    Declare that a website's HTTPS certificate should only be treated as valid if the public key is contained in a list specified over HTTP to prevent MITM attacks that use valid CA-issued certificates.

  14. attr api: specified

  15. svgangle api: converttospecifiedunits

  16. svgangle api: newvaluespecifiedunits

  17. svgangle api: valueinspecifiedunits

  18. svglength api: converttospecifiedunits

  19. svglength api: newvaluespecifiedunits

  20. svglength api: valueinspecifiedunits

  21. websocket api: supports protocol as specified by rfc 6455