Request js library Unexpected end of JSON input

Question

I am running server on node.js and Express v4.0

And i am using request library Uncaught SyntaxError: Unexpected end of JSON input then recving response from server i am getting response but without last symbol ("}") so when i try to parse JSON it throws error. The problem is that if i do same request with xmlhttprequest from Chrome it works with SAME HEADERS AND SAME BODY

request parametrs:

request({
                    method:"POST",
                    jar:true,
                    url:host+"/api/location",
                    form:{
                        longitude:elem.longitude,
                        latitude:elem.latitude
                    },
                    followAllRedirects:true
                },(err,res,body)=>{
                    logger.log(body);
                    body = JSON.parse(body);
                    assert(!body.success);
                    assert(body.longitude != elem.longitude && body.latitude != elem.latitude);
                    done();
                });

response is comming back incorrect code in express:

res.send(JSON.stringify(({
  error:"Unknown",
  errorCode:errorCode,
  success:false,
  "-_-":"_-_"
})));

last fields was a try to send another field and check is other field is malformed or not. and it wasnot malformed but still last symbol not recved.

also i tried to use res.json() with same body but no success. same result.

what i can do? is anyway to find where is problem?

Answer 1

You do not need to stringify the JSON and parse the result. You should be able to just send the JSON as a response and the 'body' in the request callback should contain the JSON from the response.

Answer 2

I fixed it.

There was error on server side that was not visible to some reasons.

res.json().end() was used two times. So body was already sent and i was trying to add something else. This is strange behavoir