This Node Stream will transform a response stream from request (https://github.com/mikeal/request) to be an object containing the status code, headers, and body. The data is emitted as an error if the response is not a 2xx.

responseStream.js

'use strict';
 
var Base, ResponseTransformStream, twoHundo;
 
Base = require('stream').Transform;
 
twoHundo = /^2\d\d$/;
 
ResponseTransformStream = function (opts) {
  Base.call(this, opts);
  this.headers = {};
  this.body = '';
};
require('util').inherits(ResponseTransformStream, Base);
 
ResponseTransformStream.prototype.setHeader = function (key, value) {
  this.headers[key] = value;
};
 
ResponseTransformStream.prototype._transform = function (chunk, enc, next) {
  this.body += String(chunk);
  next();
};

ResponseTransformStream.prototype._flush = function(next) {
  var data;
  data = {
    statusCode: this.statusCode,
    headers: this.headers,
    body: JSON.parse(this.body)
  };
  if (twoHundo.test(this.statusCode)) {
    this.push(JSON.stringify(data));
    next();
  }
  else {
    next(data);
  }
};
 
module.exports = function responseTransform (opts) {
  return new ResponseTransformStream(opts);
};