http.js

var url_parts = url.parse(req.url, true);
var query1 = url_parts.query;

  // Build the post string from an object
var query=querystring.stringify(query1);
  

var post_options = {
	  host: 'steamcommunity.com',
	  port: '443',
	  path: '/openid/login?',
	  method: 'POST',
	  headers: {
		  'Content-Type': 'application/x-www-form-urlencoded',
		  'Content-Length': Buffer.byteLength(query)
	  }
  };

  var post_req = http.request(post_options, function(res) {
	  res.setEncoding('utf-8');
	  var fullBody = '';
	 res.on('data', function (chunk) {
	 		  fullBody += chunk.toString();
	 	  });
	res.on('end', function() {
		  
	var pattern=/is_valid:true/g;
	var result = pattern.test(fullBody);
	// i need the result of this to be 
		}
		});
  });

  post_req.write(query);
  
  post_req.end();
//HERE
res.end();

request.js

var request = require('request')
  , qs      = require('querystring')
  ;

var user = {username: "cl0udy"}
  , post = 
    { method: 'POST'
    , url   : 'https://steamcommunity.com/openid/login?' + qs.stringify(user)
 // , body  : qs.stringify(user)
    }
  ;

request(post, function(err,response,body) {
  console.log(response.statusCode, body);
});