The attachShadow Element for JS creates a shadow root for element and returns it.
shadow = element.attachShadow(init)
Initialize
shadowRoot
classList
className
closest
getAttribute
getAttributeNames
getAttributeNS
hasAttribute
hasAttributeNS
hasAttributes
id
innerHTML
insertAdjacentHTML
localName
matches
namespaceURI
outerHTML
prefix
removeAttribute
removeAttributeNS
setAttribute
setAttributeNS
slot
tagName
toggleAttribute
Web Hypertext Application Technology Working Group (WHATWG)