React Native - Backbone fetch patch

index.ios.js

/**
 * patch to make backbone work on react native
 * replaces the underlying jQuery API with the whatwg fetch API
 * doesn't cover all use cases... but has worked fine with our project
 */

var Backbone = require('backbone');
var _ = require('underscore');
Backbone.sync = function(method, model, options) {

  var headers = {
    'Accept': 'application/json'
  };
  var body = '';

  var url = model.url;
  if (!options.url) {
    url = _.result(model, 'url');
  } else {
    url = options.url;
  }

  if (options.data == null && model && (method === 'create' || method === 'update' || method === 'patch')) {
    headers['Content-Type'] = 'application/json';
    body = JSON.stringify(options.attrs || model.toJSON(options));
  }

  var methodMap = {
    'create': 'POST',
    'update': 'PUT',
    'patch':  'PATCH',
    'delete': 'DELETE',
    'read':   'GET'
  };
  method = methodMap[method];

  return fetch(url, {
    method: method,
    headers: headers,
    body: body
  })
  .then(res => {
    var response = JSON.parse(res._bodyText);
    options.success(response, options);
  });
};