slot - HTML: HyperText Markup Language

mdn slot The slot property of the Element interface returns the name of the shadow DOM slot the element is inserted. When the slot's containing component gets rendered, the slot is rendered with the custom element's child that has a matching slot attribute. A named slot is a slot> element

mdnsport live chat, element .slot = aString. A DOMString. The definition of 'slot' in that specification. The slot property of the Element interface returns the name of the shadow DOM slot attached to the element. A.