Rocket.Chat/app/api/server/helpers/isUserFromParams.js

import { API } from '../api';

API.helperMethods.set('isUserFromParams', function _isUserFromParams() {
	const params = this.requestParams();

	return (!params.userId && !params.username && !params.user)
		|| (params.userId && this.userId === params.userId)
		|| (params.username && this.user.username === params.username)
		|| (params.user && this.user.username === params.user);
});