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). When working with Shadow DOM-enabled components, the element is a web platform native way to allow content projection into components. This article explains how you can use the and elements to create a flexible template that can then be used to populate the shadow DOM of a. Try checking for existing elements in connectedCalback or by listening for slotchange events dispatched by your slot element ([HOST]Root. To access children assigned to slots in your shadow root, you can use the standard [HOST]edNodes or [HOST]edElements methods with the slotchange event. Note that when applying the restamp attribute to dom-if. There are two kinds of slots: Named slots: