The slot property of the Element interface returns the name of the shadow DOM slot the element is inserted in. A slot is a placeholder inside a web component that users can fill with their own markup (see Using templates and slots for more information).

A Scoped slot provides local data from the component so that the parent can choose how to render it.

A slot is a narrow opening in a machine or container, for example a hole that you put coins in to make a machine work. He dropped a coin into the slot and dialled the number. If you slot something into something else, or if it slots into it, you put it into a space where it fits. He was slotting a CD into a CD player.

slot noun [C] (HOLE)\n\n a narrow hole or opening: Drop the letter in the mail slot.