CustomElementRegistry: upgrade() method

The upgrade() method of the CustomElementRegistry interface upgrades all shadow-containing custom elements in a Node subtree, even before they are connected to the main document.

Syntax

upgrade(root)

Parameters

root

A Node instance with shadow-containing descendant elements to upgrade. If there are no descendant elements that can be upgraded, no error is thrown.

Return value

None (undefined).

Examples

Taken from the HTML spec:

const el = document.createElement("spider-man");

class SpiderMan extends HTMLElement {}
customElements.define("spider-man", SpiderMan);

console.assert(!(el instanceof SpiderMan)); // not yet upgraded

customElements.upgrade(el);
console.assert(el instanceof SpiderMan); // upgraded!

Specifications

Browser compatibility