| CARVIEW |
Select Language
HTTP/2 200
content-type: text/html
x-guploader-uploadid: AAwnv3K1oFDNKMC4Jo6pmHmszGgJwzehCxMyDDwXrjvJdWAeVzmc3eiTDvASGn0281R1A6bT
cache-control: public, max-age=3600
expires: Tue, 14 Oct 2025 14:57:58 GMT
last-modified: Tue, 14 Oct 2025 01:05:07 GMT
etag: W/"e5f84081ebeb6b406c9d22d9d67ee30a"
x-goog-generation: 1760403907827640
x-goog-metageneration: 1
x-goog-stored-content-encoding: identity
x-goog-stored-content-length: 134735
x-goog-meta-goog-reserved-file-mtime: 1760402406
x-goog-hash: crc32c=1b2FgA==, md5=5fhAgevra0BsnSLZ1n7jCg==
x-goog-storage-class: STANDARD
accept-ranges: none
alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
alt-svc: clear
referrer-policy: strict-origin-when-cross-origin
x-content-type-options: nosniff
strict-transport-security: max-age=63072000
content-security-policy: default-src 'self'; script-src 'report-sample' 'self' 'wasm-unsafe-eval' https://www.google-analytics.com/analytics.js https://www.googletagmanager.com/gtag/js assets.codepen.io production-assets.codepen.io https://js.stripe.com 'sha256-XNBp89FG76amD8BqrJzyflxOF9PaWPqPqvJfKZPCv7M=' 'sha256-YCNoU9DNiinACbd8n6UPyB/8vj0kXvhkOni9/06SuYw=' 'sha256-PZjP7OR6mBEtnvXIZfCZ5PuOlxoDF1LDZL8aj8c42rw='; script-src-elem 'report-sample' 'self' 'wasm-unsafe-eval' https://www.google-analytics.com/analytics.js https://www.googletagmanager.com/gtag/js assets.codepen.io production-assets.codepen.io https://js.stripe.com 'sha256-XNBp89FG76amD8BqrJzyflxOF9PaWPqPqvJfKZPCv7M=' 'sha256-YCNoU9DNiinACbd8n6UPyB/8vj0kXvhkOni9/06SuYw=' 'sha256-PZjP7OR6mBEtnvXIZfCZ5PuOlxoDF1LDZL8aj8c42rw='; style-src 'report-sample' 'self' 'unsafe-inline'; object-src 'none'; base-uri 'self'; connect-src 'self' developer.allizom.org bcd.developer.allizom.org bcd.developer.mozilla.org updates.developer.allizom.org updates.developer.mozilla.org https://*.google-analytics.com https://*.analytics.google.com https://*.googletagmanager.com https://incoming.telemetry.mozilla.org https://observatory-api.mdn.allizom.net https://observatory-api.mdn.mozilla.net https://api.github.com/search/issues stats.g.doubleclick.net https://api.stripe.com; font-src 'self'; frame-src 'self' interactive-examples.mdn.mozilla.net interactive-examples.mdn.allizom.net mdn.github.io live-samples.mdn.mozilla.net live-samples.mdn.allizom.net *.mdnplay.dev *.mdnyalp.dev *.play.test.mdn.allizom.net https://v2.scrimba.com https://scrimba.com jsfiddle.net www.youtube-nocookie.com codepen.io survey.alchemer.com https://js.stripe.com; img-src 'self' data: *.githubusercontent.com *.googleusercontent.com *.gravatar.com mozillausercontent.com firefoxusercontent.com profile.stage.mozaws.net profile.accounts.firefox.com developer.mozilla.org mdn.dev interactive-examples.mdn.mozilla.net interactive-examples.mdn.allizom.net wikipedia.org upload.wikimedia.org https://mdn.github.io/shared-assets/ https://mdn.dev/ https://*.google-analytics.com https://*.googletagmanager.com www.gstatic.com; manifest-src 'self'; media-src 'self' archive.org videos.cdn.mozilla.net https://mdn.github.io/shared-assets/; child-src 'self'; worker-src 'self';
x-frame-options: DENY
origin-trial: AxVILwizhbMjxFeHOn1P3R8niO1RJY/smaK4B4d1rLzc1gTaxtXMSaTi+FoigYgCw40uFRDwFcEAeqDR+vVLOW4AAABfeyJvcmlnaW4iOiJodHRwczovL2RldmVsb3Blci5tb3ppbGxhLm9yZyIsImZlYXR1cmUiOiJQcml2YXRlQXR0cmlidXRpb25WMiIsImV4cGlyeSI6MTc0MjA3OTYwMH0=
x-cloud-trace-context: 21e12932f4e4ea8f88760d7f7883339d
date: Tue, 14 Oct 2025 13:57:59 GMT
server: Google Frontend
via: 1.1 google
vary: Accept-Encoding
content-encoding: gzip
x-cache: miss
CustomStateSet: add() method - Web APIs | MDN
CustomStateSet: add() method
Baseline
2024
Newly available
Since May 2024, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.
The add method of the CustomStateSet interface adds value representing a custom state to the CustomStateSet.
Custom elements with a specific state can be selected using the :state() pseudo-class, specifying the desired state as an argument.
Syntax
js
add(value)
Parameters
value-
A string that represents the custom state.
Return value
Undefined.
Examples
The following function adds the state checked to a CustomStateSet.
js
class MyCustomElement extends HTMLElement {
set checked(flag) {
if (flag) {
this._internals.states.add("checked");
}
}
}
Specifications
| Specification |
|---|
| HTML # custom-state-pseudo-class |
Browser compatibility
Loading…