rails and ajax SyntaxError {stack: (...), message: "Unexpected token <"} - ruby-on-rails

Question

I'm trying to execute a ajax every 5 seconds an get the json result. But the ajax it's not working I always get:
SyntaxError {stack: (...), message: "Unexpected token <"}
$(document).ready(function(){
setInterval(function(){
var url = "/hangout_second_user";
$.ajax({
url: url,
type: "GET",
data: {"username" : "someusername"},
dataType: 'json',
success: function(){
alert(result);
},
error: function(xhr, textStatus, error) {
console.log("Impossible to connect");
console.log(xhr.statusText);
console.log(textStatus);
console.log(error);
}
});
}, 5000);
});
Here is the action of my controller:
def hangout_second_user
#incoming_kid = Kid.where(username: params[:username]).first
prueba = REDIS.smembers "hangout:#{current_kid.id.to_s}"
if !prueba.empty?
current_kid.set_busy_status!
respond_to do |format|
format.json { render json: "{url:#{prueba[0].to_s}}", success: :ok, error: false }
end
end
end
UPDATE
I changed the render format like this:
format.json { render json: prueba[0].to_json, success: :ok, error: false }
but I still getting and html file and that's why I'm getting an error. Any help please

Answer 1

You should use either the $.ajax() function or the $.getJSON() function, as $.getJSON() will also perform an AJAX call.
So a possible solution would be:
setInterval(function(){
var url = "/hangout_second_user";
$.ajax({
url: url,
data: {"user_id" : "537c63ea20db9040d2000332"},
dataType: 'json',
success: function(result){
$.each(result, function(i, field){
alert(result);
});
},
error: function(xhr, textStatus, error) {
console.log("Impossible to connect");
console.log(xhr.statusText);
console.log(textStatus);
console.log(error);
}
});
}, 5000);
Or alternatively:
setInterval(function(){
var url = "/hangout_second_user";
$.getJSON(url, {"user_id" : "537c63ea20db9040d2000332"}; function(result) {
$.each(result, function(i, field){
alert(result);
});
});
}, 5000);

Answer 2

You cant use "#{current_kid.id.to_s}" in javascript. Try storing its value somewhere in hidden _field and access it in javascript