• HTML:
  • MessagePort: postMessage(message, transfer), postMessage(message, { transfer })
  • Window: postMessage(message, targetOrigin, transfer), postMessage(message, { transfer, targetOrigin })
  • BroadcastChannel: postMessage(message)
  • DedicatedWorkerGlobalScope: postMessage(message, transfer), postMessage(message, { transfer })
  • Worker: postMessage(message, transfer), postMessage(message, { transfer })
• Service Workers:
  • Client: postMessage(message, transfer), postMessage(message, { transfer })
  • ServiceWorker: postMessage(message, transfer), postMessage(message, { transfer })
• Portals:
  • HTMLPortalElement: postMessage(message, { transfer })
  • PortalHost: postMessage(message, { transfer })

Warning: this is no longer kept up-to-date.

Custom elements is a feature that, until recently, was developed as monkey patches onto various specifications. This page helps implementers get a consolidated view of how custom elements have changed the HTML Standard.

These are the affected sections:

• Elements in the DOM:
  • The HTMLElement constructor
  • The definition of "element interface"
• Custom elements
• Window got a new customElements attribute
• Creating and inserting nodes: create an element for a token
• The XML syntax now mentions that "create an element for a token" must be used.
• Various places now use the "create an element" hook introduced to the DOM Standard for creating elements:
  • document.title
  • table-created
  • insertRow()
  • insertCell()
  • Audio() constructor
  • Image() constructor
  • Option() constructor
• All throughout the spec: [CEReactions] extended attributes are now present

All relevant commits can be found in the list of pull requests tagged "topic: custom elements".

You may also be interested in similar information for changes to the DOM Standard.