CustomElementRegistry

The CustomElementRegistry is a global object in web browsers that provides an interface for defining and managing custom HTML elements. It is a core part of the Custom Elements API, which allows developers to extend HTML with their own elements that have custom behavior and styling. When you define a custom element using the `customElements.define()` method, you are registering it with the CustomElementRegistry.

The registry stores a mapping between the custom element's tag name (e.g., "my-component") and its associated class constructor. This class is responsible for defining the element's lifecycle callbacks, such as when it is connected to the DOM, when it is disconnected, and when its attributes change. The CustomElementRegistry ensures that when the browser encounters a tag name that has been registered, it instantiates the corresponding custom element class and attaches it to the DOM.

There are limitations on the names that can be used for custom elements. They must contain a hyphen to distinguish them from standard HTML elements and avoid naming collisions. The CustomElementRegistry also handles the creation of new instances of custom elements when they are parsed from HTML or created programmatically. It plays a crucial role in the extensibility of the web platform, enabling developers to create reusable, encapsulated components.