Very simple remark plugins for tags, mentions and comment.

comment.js

import { findAndReplace } from "mdast-util-find-and-replace";

const commentRegex = /\/\/([^\n\\/]*)\/\//g; // //<value>//

export default function () {
	function replaceComment(_match, text) {
		return {
			type: "span",
			data: {
				hName: "comment",
				hProperties: { text }
			}
		};
	}

	function transformer(tree) {
		findAndReplace(tree, commentRegex, replaceComment);
	}

	return transformer;
}

mention.js

import { findAndReplace } from "mdast-util-find-and-replace";

const mentionRegex = /@([^\n(]+)[(]([A-Z0-9]{5})?[)]/g; // @<value>(<5-characters-id>)

export default function () {
	function replaceMention(_match, alias, id = "00000") {
		return {
			type: "span",
			data: {
				hName: "mention",
				hProperties: { alias, id }
			}
		};
	}

	function transformer(tree) {
		findAndReplace(tree, mentionRegex, replaceMention);
	}

	return transformer;
}

tag.js

import { findAndReplace } from "mdast-util-find-and-replace";

const tagRegex = /#(\S+)/g; // #<value>

export default function () {
	function replaceTag(_match, label) {
		const cleanLabel = label.replace(/_/g, " "); // Supports multi-word tag

		return {
			type: "span",
			data: {
				hName: "tag",
				hProperties: { label: cleanLabel }
			}
		};
	}

	function transformer(tree) {
		findAndReplace(tree, tagRegex, replaceTag);
	}

	return transformer;
}