HTMLSlotElement: assn() method - Web APIs | MDN -

mdn slot login A named slot is a slot> element with a name attribute. Unnamed slots have the name default to the empty string. Names should be unique. slot はグローバルでシャドウ DOM のシャドウツリーにあるスロットをあるにりてます slot をもつには slot> に name のをすることで

mdn slot, You can have multiple elements assned to the same slot by using the same slot name. Elements without a slot attribute are assned to the unnamed slot, if one exists..