window.customElements

The customElements read-only property of the Window interface returns a reference to the CustomElementRegistry object, which can be used to register new custom elements and get information about previously registered custom elements.

Syntax

let customElementRegistry = window.customElements;

Return value

A CustomElementRegistry object instance representing the custom element registry for the current window.

Examples

The most common example you'll see of this property being used is to get access to the CustomElementRegistry.define() method to define and register a new custom element, e.g.:

let customElementRegistry = window.customElements;
customElementRegistry.define('my-custom-element', MyCustomElement);

However, it is usually shortened to something like the following:

customElements.define('element-details',
  class extends HTMLElement {
    constructor() {
      super();
      const template = document
        .getElementById('element-details-template')
        .content;
      const shadowRoot = this.attachShadow({mode: 'open'})
        .appendChild(template.cloneNode(true));
  }
});

See our web-components-examples repo for more usage examples.

Specification

Browser compatibilityUpdate compatibility data on GitHub