How about just checking

/^[^a-zA-Z0-9]+$/.test(helper.state.query)

to check if query string contains only alpha numeric? That can be added along with the empty string check here: https://github.com/typesense/showcase-songs-search/blob/e7ad97ce4e09191743abd727c2dfc949811bbcd6/src/app.js#L176