HttpCheck in node.js

One of the most useful tools when you develop mobile portals is a simple web page to check the headers your browser is sending to the server. Which User-Agent? Accept-Language? Accept-Encoding? Accept-Charset?

A good opportunity to write a tiny node.js application (with just a bit of Underscore magic).

var http = require('http'), 
    _ = require('./underscore'),
    port = process.env.PORT || 3000;

var FullResponse = function(req) {

  var blanks = "                                   ";
  var fields = {"url": req.url, "method": req.method, "httpVersion": req.httpVersion, 
              "headers": req.headers, "data": ""};  
    
  var format = function(key, value, indent) {    
    if (_.isString(value))
      var valuePart = value+"\n";
    else
      var valuePart = "\n" + _.reduce(_.keys(value), function(sum, it) {  
        return sum + format(it, value[it], indent+1);  }, 
        "");
          
    return blanks.substring(0, indent * 2) + key+": " + valuePart;
  }        
  
  this.addData = function(data) {
    fields["data"] += data.toString("utf8");
  }
  
  this.printOut = function() {        
    return format("response", fields, 0);
  }
  
}

http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  var response = new FullResponse(req);  
  req.on("data", function(it) {
    response.addData(it);
  });  
  req.on("end", function() {
    res.end(response.printOut());  
  });  
}).listen(port);
console.log('Server running at port '+port);

Full source code on Github, the application is running at http://httpcheck.herokuapp.com.