browser.js

'use strict';

var Response = require('http-response-object');
var handleQs = require('then-request/lib/handle-qs.js');

module.exports = doRequest;
function doRequest(method, url, options) {
  var xhr = new XMLHttpRequest();

  // check types of arguments

  if (typeof method !== 'string') {
    throw new TypeError('The method must be a string.');
  }
  if (typeof url !== 'string') {
    throw new TypeError('The URL/path must be a string.');
  }
  if (options === null || options === undefined) {
    options = {};
  }
  if (typeof options !== 'object') {
    throw new TypeError('Options must be an object (or null).');
  }
  
  method = method.toUpperCase();
  options.headers = options.headers || {};

  // handle cross domain

  var match;
  var crossDomain = !!((match = /^([\w-]+:)?\/\/([^\/]+)/.exec(options.uri)) && (match[2] != location.host));
  if (!crossDomain) options.headers['X-Requested-With'] = 'XMLHttpRequest';

  // handle query string
  if (options.qs) {
    url = handleQs(url, options.qs);
  }

  // handle json body
  if (options.json) {
    options.body = JSON.stringify(options.json);
    options.headers['content-type'] = 'application/json';
  }

  // method, url, async
  xhr.open(method, url, false);

  for (var name in options.headers) {
    xhr.setRequestHeader(name.toLowerCase(), options.headers[name]);
  }

  // avoid sending empty string (#319)
  xhr.send(options.body ? options.body : null);


  var headers = {};
  xhr.getAllResponseHeaders().split('\r\n').forEach(function (header) {
    var h = header.split(':');
    if (h.length > 1) {
      headers[h[0].toLowerCase()] = h.slice(1).join(':').trim();
    }
  });
  return new Response(xhr.status, headers, xhr.responseText);
}