CustomElementRegistry

Baseline Widely available *

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨January 2020⁩.

* Some parts of this feature may have varying levels of support.

The CustomElementRegistry interface provides methods for registering custom elements and querying registered elements. To get an instance of it, use the window.customElements property.

Instance methods

CustomElementRegistry.define(): Defines a new custom element.
CustomElementRegistry.get(): Returns the constructor for the named custom element, or undefined if the custom element is not defined.
CustomElementRegistry.getName(): Returns the name for the already-defined custom element, or null if the custom element is not defined.
CustomElementRegistry.upgrade(): Upgrades a custom element directly, even before it is connected to its shadow root.
CustomElementRegistry.whenDefined(): Returns an empty Promise that resolves when a custom element becomes defined with the given name. If such a custom element is already defined, the returned promise is immediately fulfilled.

Examples

See the Examples section in our guide to using custom elements.

Specifications

Specification
HTML # custom-elements-api

Browser compatibility

Help improve MDN

Learn how to contribute

This page was last modified on ⁨Sep 27, 2023⁩ by MDN contributors.

View this page on GitHub • Report a problem with this content