text: /**
   * Copyright (c) 2015-present, Facebook, Inc.
   * All rights reserved.
   *
   * This source code is licensed under the BSD-style license found in the
   * LICENSE file in the root directory of this source tree. An additional grant
   * of patent rights can be found in the PATENTS file in the same directory.
   *
   * @providesModule FormData
   * @flow
   */
  'use strict';
  
  type FormDataValue = any;
  type FormDataNameValuePair = [string, FormDataValue];
  
  type Headers = {[name: string]: string};
  type FormDataPart = {
    string: string,
    headers: Headers,
  } | {
    uri: string,
    headers: Headers,
    name?: string,
    type?: string,
  };
  
  /**
   * Polyfill for XMLHttpRequest2 FormData API, allowing multipart POST requests
   * with mixed data (string, native files) to be submitted via XMLHttpRequest.
   *
   * Example:
   *
   *   var photo = {
   *     uri: uriFromCameraRoll,
   *     type: 'image/jpeg',
   *     name: 'photo.jpg',
   *   };
   *
   *   var body = new FormData();
   *   body.append('authToken', 'secret');
   *   body.append('photo', photo);
   *   body.append('title', 'A beautiful photo!');
   *
   *   xhr.open('POST', serverURL);
   *   xhr.send(body);
   */
  class FormData {
    _parts: Array<FormDataNameValuePair>;
  
    constructor() {
      this._parts = [];
    }
  
    append(key: string, value: FormDataValue) {
      // The XMLHttpRequest spec doesn't specify if duplicate keys are allowed.
      // MDN says that any new values should be appended to existing values.
      // In any case, major browsers allow duplicate keys, so that's what we'll do
      // too. They'll simply get appended as additional form data parts in the
      // request body, leaving the server to deal with them.
      this._parts.push([key, value]);
    }
  
    getParts(): Array<FormDataPart> {
      return this._parts.map(([name, value]) => {
        var contentDisposition = 'form-data; name="' + name + '"';
  
        var headers: Headers = {'content-disposition': contentDisposition};
  
        // The body part is a "blob", which in React Native just means
        // an object with a `uri` attribute. Optionally, it can also
        // have a `name` and `type` attribute to specify filename and
        // content type (cf. web Blob interface.)
        if (typeof value === 'object' && value) {
          if (typeof value.name === 'string') {
            headers['content-disposition'] += '; filename="' + value.name + '"';
          }
          if (typeof value.type === 'string') {
            headers['content-type'] = value.type;
          }
          return {...value, headers, fieldName: name};
        }
        // Convert non-object values to strings as per FormData.append() spec
        return {string: String(value), headers, fieldName: name};
      });
    }
  }
  
  module.exports = FormData;
  