How to get GET (query string) variables in Express.js on Node.js?

Since you've mentioned Express.js in your tags, here is an Express-specific answer: use req.query. E.g.

var express = require('express');
var app = express();

app.get('/', function(req, res){
  res.send('id: ' + req.query.id);
});

app.listen(3000);

In Express, use req.query.

req.params only gets the route parameters, not the query string parameters. See the express or sails documentation:

(req.params) Checks route params, ex: /user/:id

(req.query) Checks query string params, ex: ?id=12 Checks urlencoded body params

(req.body), ex: id=12 To utilize urlencoded request bodies, req.body should be an object. This can be done by using the _express.bodyParser middleware.

That said, most of the time, you want to get the value of a parameter irrespective of its source. In that case, use:

req.param('foo')

The value of the parameter will be returned whether the variable was in the route parameters, query string, or the encoded request body.

Side note- if you're aiming to get the intersection of all three types of request parameters (similar to PHP's $_REQUEST), you just need to merge the parameters together-- here's how I set it up in Sails. Keep in mind that the path/route parameters object (req.params) has array properties, so order matters (although this may change in Express 4)

For Express.js you want to do req.params:

app.get('/user/:id', function(req, res) {
  res.send('user' + req.params.id);    
});

I learned from the other answers and decided to use this code throughout my site:

var query = require('url').parse(req.url,true).query;

Then you can just call

var id = query.id;
var option = query.option;

where the URL for get should be

/path/filename?id=123&option=456

You should be able to do something like this:

var http = require('http');
var url  = require('url');

http.createServer(function(req,res){
    var url_parts = url.parse(req.url, true);
    var query = url_parts.query;

    console.log(query); //{Object}

    res.end("End")
})

UPDATE 4 May 2014

Old answer preserved here: https://gist.github.com/stefek99/b10ed037d2a4a323d638

1) Install express: npm install express

app.js

var express = require('express');
var app = express();

app.get('/endpoint', function(request, response) {
    var id = request.query.id;
    response.end("I have received the ID: " + id);
});

app.listen(3000);
console.log("node express app started at http://localhost:3000");

2) Run the app: node app.js

3) Visit in the browser: http://localhost:3000/endpoint?id=something

I have received the ID: something

(many things have changed since my answer and I believe it is worth keeping things up to date)

A small Node.js HTTP server listening on port 9080, parsing GET or POST data and sending it back to the client as part of the response is:

var sys = require('sys'),
url = require('url'),
http = require('http'),
qs = require('querystring');

var server = http.createServer(

    function (request, response) {

        if (request.method == 'POST') {
                var body = '';
                request.on('data', function (data) {
                    body += data;
                });
                request.on('end',function() {

                    var POST =  qs.parse(body);
                    //console.log(POST);
                    response.writeHead( 200 );
                    response.write( JSON.stringify( POST ) );
                    response.end();
                });
        }
        else if(request.method == 'GET') {

            var url_parts = url.parse(request.url,true);
            //console.log(url_parts.query);
            response.writeHead( 200 );
            response.write( JSON.stringify( url_parts.query ) );
            response.end();
        }
    }
);

server.listen(9080);

Save it as parse.js, and run it on the console by entering "node parse.js".

Whitequark responded nicely. But with the current versions of Node.js and Express.js it requires one more line. Make sure to add the 'require http' (second line). I've posted a fuller example here that shows how this call can work. Once running, type http://localhost:8080/?name=abel&fruit=apple in your browser, and you will get a cool response based on the code.

var express = require('express');
var http = require('http');
var app = express();

app.configure(function(){
    app.set('port', 8080);
});

app.get('/', function(req, res){
  res.writeHead(200, {'content-type': 'text/plain'});
  res.write('name: ' + req.query.name + '\n');
  res.write('fruit: ' + req.query.fruit + '\n');
  res.write('query: ' + req.query + '\n');
  queryStuff = JSON.stringify(req.query);
  res.end('That\'s all folks'  + '\n' + queryStuff);
});

http.createServer(app).listen(app.get('port'), function(){
    console.log("Express server listening on port " + app.get('port'));
})

It is so simple:

Example URL:

http://stackoverflow.com:3000/activate_accountid=3&activatekey=$2a$08$jvGevXUOvYxKsiBt.PpMs.zgzD4C/wwTsvjzfUrqLrgS3zXJVfVRK

You can print all the values of query string by using:

console.log("All query strings: " + JSON.stringify(req.query));

Output

All query strings : { "id":"3","activatekey":"$2a$08$jvGevXUOvYxKsiBt.PpMs.zgzD4C/wwTsvjz fUrqLrgS3zXJVfVRK"}

To print specific:

console.log("activatekey: " + req.query.activatekey);

Output

activatekey: $2a$08$jvGevXUOvYxKsiBt.PpMs.zgzD4C/wwTsvjzfUrqLrgS3zXJVfVRK