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/Web APIs

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

js

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:

js

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

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
upgrade 68 79 63 No 55 12.1 68 68 63 48 12.2 10.0

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https://developer.mozilla.org/en-US/docs/Web/API/CustomElementRegistry/upgrade