Jquery Ajax call works with HTML but not JSON -

i have started work drupal 8 , doing ajax calls server using fresh controller system implemented drupal team.

my problem occurs when have defined route , make ajax call using jquery. if set datatype "json" receive 404, changing "html" work.

the function route points looks this:

function createresponse(){     return new jsonresponse(['data' => 'test']); } 

my response/request-headers this:

response

cache-control   must-revalidate, no-cache, post-check=0, pre-check=0, private connection  keep-alive content-encoding    gzip content-language    en content-type    application/json date    wed, 19 nov 2014 12:20:35 gmt expires sun, 19 nov 1978 05:00:00 gmt keep-alive  timeout=10 server  nginx transfer-encoding   chunked vary    accept-encoding x-powered-by    php/5.5.18-1~dotdeb.1 x-ua-compatible ie=edge,chrome=1 

request header

accept  application/json, text/javascript, */*; q=0.01 accept-encoding gzip, deflate accept-language en-us,en;q=0.5 content-length  9 content-type    application/json; charset=utf-8 host    d8test.local referer http://d8test.local/ user-agent  mozilla/5.0 (windows nt 6.3; wow64; rv:33.0) gecko/20100101 firefox/33.0 x-requested-with    xmlhttprequest 

is drupal 8 specific? there stupid variable forbidding json xmlhttprequests? can access route surfing route , can data using html need in json-format.

this jquery code:

jquery.ajax({       url: drupalsettings.path.basepath + "testajax",       type: "post",       contenttype: "application/json; charset=utf-8",       datatype: "json",       data: {'type' : 'list'},       success: function(data){           console.log(data);       } }); 

testajax route have defined, works fine , work if change datatype "html" feels weird.

thanks vital clues spokey in comments found out problem, route wrongly setup in drupal. instead of _controller used _content. _controller accesses function without adding lots of markup-overhead.

so if bump problem yourself, make sure routes.yml file has _controller setting , not _content one.