Some bare-bones Request/Response prototypes for JavaScript. Wraps XMLHttpRequest.

request.js

/**
 * Request class for making HTTP requests.
 *
 *    new Request('http://api.com', {
 *      method: 'get',
 *      headers: {}
 *    }).send(function(res) {});
 */
function Request(url, opts) {
  opts = opts || {};
  this.url = url;
  this.headers = opts.headers || {};
  this.method = opts.method || 'get';
}

/**
 * Sends the request object. Accepts and callback function
 * that receives a Response object.
 */
Request.prototype.send = function sendRequest(callback) {
  var request = new XMLHttpRequest();
  var self = this;

  /**
   * Callback wrapper that creates a #Response object.
   */
  request.onload = function handleResponse() {
    var res = new Response(request);
    callback.call(self, res);
  };

  /**
   * Opens the XMLHttpRequest so headers can be set.
   */
  request.open(this.method, this.url);

  /**
   * Sets requet headers from the @headers property.
   */
  Object.keys(this.headers).forEach(function setHeader(header) {
    request.setRequestHeader(header, this.headers[header]);
  }, this);

  /**
   * Sends the request
   */
  request.send();

  return this;
};

/**
 * Convenience method for sending a get request
 * without having to create an instance.
 */
Request.get = function get(url, headers, callback) {
  if (arguments.length < 3) {
    callback = headers;
  }

  return new Request(url, {
    method: 'get',
    headers: headers || {}
  }).send(callback);
};


/**
 * Reponse class. Wraps an XMLHttpRequest instance.
 */
function Response(xmlreq) {
  if (xmlreq) {
    this.status = xmlreq.status;
    this._parseHeaders(xmlreq.getAllResponseHeaders());

    if (this.headers['Content-Type'] && /application\/json/.test(this.headers['Content-Type'])) {
      this.body = JSON.parse(xmlreq.responseText);
    } else {
      this.body = xmlreq.responseText || '';
    }
  }
}

/**
 * Parses a header string into a @headers property.
 */
Response.prototype._parseHeaders = function parseHeaders(headers) {
  var splitHeaders = headers.split('\n');
  var headerRegExp = /^(.*):(.*)$/;
  var headersMap = {};

  splitHeaders.forEach(function processHeader(header) {
    var strippedHeader = header.replace(/\s/mg, '');
    var headerParsed = headerRegExp.exec(strippedHeader);

    if (headerParsed && headerParsed.length >= 3) {
      headersMap[headerParsed[1]] = headerParsed[2];
    }
  });

  this.headers = headersMap;

  return this;
};