Need help editing a JavaScript function

I am trying to write a JavaScript function in react JS to interact with Google firebase, but it does not appear to be working the way I want it to. const watchlistChecker = () => { // [login to view URL](stock); [login to view URL]((watchlistItem) => { if ([login to view URL] === [login to view URL]) { return ( <button className="watchlist_btn" onClick={deleteWatchlistItemHandler}> Remove from Watchlist </button> ); } }); return ( <button className="watchlist_btn" onClick={postDataHandler}> Add to Watchlist </button> ); } The objective to display the proper button depending if the item is in the database.