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

Specification Status Comment
HTML Living Standard
The definition of 'customElements.upgrade()' in that specification.
Living Standard Initial definition.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
upgrade
Experimental
Chrome Full support 68Edge No support NoFirefox Full support 63IE No support NoOpera Full support 55Safari ? WebView Android Full support 68Chrome Android Full support 68Edge Mobile No support NoFirefox Android Full support 63Opera Android Full support 55Safari iOS ? Samsung Internet Android ?

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.

Document Tags and Contributors

Contributors to this page: mdnwebdocs-bot, chrisdavidmills, ruphin
Last updated by: mdnwebdocs-bot,