asp.net core getJSON data to javascript not working

I have a div id=title and input id=titleArea. I want to check if titleArea content exists before posting. I tried with getJSON but I understood I cannot get boolean values so I am getting string. emptu or not empty. The id is sent from script, I've checked that but no data is received

View script

JSON

public async Task OnGetCheckTitle(string id)
        {
            var checkTitle = await _context.BlogDatas.Where(s => s.Title == id).Select(s => s.BID).SingleOrDefaultAsync();

            return new JsonResult(checkTitle);
        }