addStyleSheetExternal

addStyleSheetExternal(document, text) is the single-entry fetch-or-parse path used by addStyleSheets. A value starting with http is fetched and parsed into a CSSStyleSheet; any other string is passed through sheet(). The result is cached, so one request services every custom element that wants the same URL and all of them reference the same object. The resolved sheet is then adopted on document via addAdoptedStyleSheet.

The adoption is asynchronous: the function returns immediately and the sheet appears once the fetch (or parse) settles.

Arguments

Argument	Type	Description
document	Document | ShadowRoot	Target whose adoptedStyleSheets to add to.
text	string	A http-prefixed URL to fetch, or a CSS string.

Examples

Adopt a remote stylesheet

Fetches a stylesheet by URL and adopts it once the request settles. The second call reuses the cached request and the same sheet object.

import { addStyleSheetExternal } from 'pota/use/css'

addStyleSheetExternal(document, 'https://example.com/theme.css')

// later, anywhere — no second request, same CSSStyleSheet
addStyleSheetExternal(document, 'https://example.com/theme.css')

Adopt an inline CSS string

A value that does not start with http is parsed through sheet() instead of being fetched.

import { addStyleSheetExternal } from 'pota/use/css'

addStyleSheetExternal(document, 'body { background: black }')