rudeshark.net/packages/client/src/scripts/extract-url-from-mfm.ts

import * as mfm from "mfm-js";
import { unique } from "@/scripts/array";

// unique without hash
// [ http://a/#1, http://a/#2, http://b/#3 ] => [ http://a/#1, http://b/#3 ]
const removeHash = (x: string) => x.replace(/#[^#]*$/, "");

export function extractUrlFromMfm(
	nodes: mfm.MfmNode[],
	respectSilentFlag = true,
): string[] {
	const urlNodes = mfm.extract(nodes, (node) => {
		return (
			node.type === "url" ||
			(node.type === "link" && (!(respectSilentFlag && node.props.silent)))
		);
	});
	const urls: string[] = unique(urlNodes.map((x) => x.props.url));

	return urls.reduce((array, url) => {
		const urlWithoutHash = removeHash(url);
		if (!array.map((x) => removeHash(x)).includes(urlWithoutHash))
			array.push(url);
		return array;
	}, [] as string[]);
}