CODEWITHSUNDEEP
javascriptjsonnode.js
user6275623
user6275623

Reputation:

Undefined value in the response when sending JSON object to the client- Node.js

I am new to Node.js and JavaScript and I was hoping to get some help after searching and being unable to find a solution.

I am trying to send a JSON object to the Node.js server containing an array of 2 elements (longitude and latitude) using the XMLHttpRequest method. This is the Client-side JavaScript code:

function getLocation() {
    if (navigator.geolocation) {
        navigator.geolocation.getCurrentPosition(function(position) {
            var location = [position.coords.latitude, position.coords.longitude];
            console.log(location);
            var xhr = new XMLHttpRequest();
            xhr.open('POST', 'http://localhost:3000/locationdata', true);
            xhr.setRequestHeader('Content-Type', 'application/json');
            xhr.onload = function () {
                console.log(this.responseText);
            };
            xhr.send(location);
        });
    } else { 
        console.log('Geolocation is not supported by this browser.');
    }
}

The server receives the object without any issue. However, when I try to send the object back to the client, I get an undefined value as the response. Here is the Node.js script:

var html = 
fs.readFile(__dirname + '\\public\\index.html', function(err, data) {
    if (err){
        throw err;
    }
    htmlFile = data;
});

    var server = http.createServer(function (request, response) {

            if (request.url == "/") {
                response.writeHead(200, {"Content-Type": "text/html"});
                response.write(htmlFile);
                break;
            };

            if (request.method == 'POST' && request.url == "/locationdata") {
                var postdata = '';
                var body = '';
                request.on('data', function (data) {
                    body += data;
                });
                request.on('end', function() {
                    var postdata = body;
                    console.log(postdata);
                });
                response.writeHead(200, {"Content-Type": "application/json"});
                response.write(JSON.stringify(postdata));
            }
        response.end();
    });

    server.listen(3000);

It might be that I am sending the response before the actual request has ended but I am not sure. Any ideas?

Upvotes: 0

Views: 1520

Answers (1)

tcooc
tcooc

Reputation: 21209

You are not waiting for the request data before responding, which causes you to respond with nothing. Do this instead:

        if (request.method == 'POST' && request.url == "/locationdata") {
            var body = '';
            request.on('data', function (data) {
                body += data;
            });
            request.on('end', function() {
                response.writeHead(200, {"Content-Type": "application/json"});
                response.end(body);
            });
            return;
        }

Upvotes: 1

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