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CustomElementRegistry.upgrade()

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

customElements.upgrade(root);

Parameters

root

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

Return value

Void.

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

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