(function (factory) {
  typeof define === 'function' && define.amd ? define(factory) :
  factory();
}((function () { 'use strict';

  function _classCallCheck(instance, Constructor) {
    if (!(instance instanceof Constructor)) {
      throw new TypeError("Cannot call a class as a function");
    }
  }

  function _defineProperties(target, props) {
    for (var i = 0; i < props.length; i++) {
      var descriptor = props[i];
      descriptor.enumerable = descriptor.enumerable || false;
      descriptor.configurable = true;
      if ("value" in descriptor) descriptor.writable = true;
      Object.defineProperty(target, descriptor.key, descriptor);
    }
  }

  function _createClass(Constructor, protoProps, staticProps) {
    if (protoProps) _defineProperties(Constructor.prototype, protoProps);
    if (staticProps) _defineProperties(Constructor, staticProps);
    return Constructor;
  }

  function _inherits(subClass, superClass) {
    if (typeof superClass !== "function" && superClass !== null) {
      throw new TypeError("Super expression must either be null or a function");
    }

    subClass.prototype = Object.create(superClass && superClass.prototype, {
      constructor: {
        value: subClass,
        writable: true,
        configurable: true
      }
    });
    if (superClass) _setPrototypeOf(subClass, superClass);
  }

  function _getPrototypeOf(o) {
    _getPrototypeOf = Object.setPrototypeOf ? Object.getPrototypeOf : function _getPrototypeOf(o) {
      return o.__proto__ || Object.getPrototypeOf(o);
    };
    return _getPrototypeOf(o);
  }

  function _setPrototypeOf(o, p) {
    _setPrototypeOf = Object.setPrototypeOf || function _setPrototypeOf(o, p) {
      o.__proto__ = p;
      return o;
    };

    return _setPrototypeOf(o, p);
  }

  function _isNativeReflectConstruct() {
    if (typeof Reflect === "undefined" || !Reflect.construct) return false;
    if (Reflect.construct.sham) return false;
    if (typeof Proxy === "function") return true;

    try {
      Boolean.prototype.valueOf.call(Reflect.construct(Boolean, [], function () {}));
      return true;
    } catch (e) {
      return false;
    }
  }

  function _assertThisInitialized(self) {
    if (self === void 0) {
      throw new ReferenceError("this hasn't been initialised - super() hasn't been called");
    }

    return self;
  }

  function _possibleConstructorReturn(self, call) {
    if (call && (typeof call === "object" || typeof call === "function")) {
      return call;
    }

    return _assertThisInitialized(self);
  }

  function _createSuper(Derived) {
    var hasNativeReflectConstruct = _isNativeReflectConstruct();

    return function _createSuperInternal() {
      var Super = _getPrototypeOf(Derived),
          result;

      if (hasNativeReflectConstruct) {
        var NewTarget = _getPrototypeOf(this).constructor;

        result = Reflect.construct(Super, arguments, NewTarget);
      } else {
        result = Super.apply(this, arguments);
      }

      return _possibleConstructorReturn(this, result);
    };
  }

  function _superPropBase(object, property) {
    while (!Object.prototype.hasOwnProperty.call(object, property)) {
      object = _getPrototypeOf(object);
      if (object === null) break;
    }

    return object;
  }

  function _get(target, property, receiver) {
    if (typeof Reflect !== "undefined" && Reflect.get) {
      _get = Reflect.get;
    } else {
      _get = function _get(target, property, receiver) {
        var base = _superPropBase(target, property);

        if (!base) return;
        var desc = Object.getOwnPropertyDescriptor(base, property);

        if (desc.get) {
          return desc.get.call(receiver);
        }

        return desc.value;
      };
    }

    return _get(target, property, receiver || target);
  }

  var Emitter = /*#__PURE__*/function () {
    function Emitter() {
      _classCallCheck(this, Emitter);

      Object.defineProperty(this, 'listeners', {
        value: {},
        writable: true,
        configurable: true
      });
    }

    _createClass(Emitter, [{
      key: "addEventListener",
      value: function addEventListener(type, callback, options) {
        if (!(type in this.listeners)) {
          this.listeners[type] = [];
        }

        this.listeners[type].push({
          callback: callback,
          options: options
        });
      }
    }, {
      key: "removeEventListener",
      value: function removeEventListener(type, callback) {
        if (!(type in this.listeners)) {
          return;
        }

        var stack = this.listeners[type];

        for (var i = 0, l = stack.length; i < l; i++) {
          if (stack[i].callback === callback) {
            stack.splice(i, 1);
            return;
          }
        }
      }
    }, {
      key: "dispatchEvent",
      value: function dispatchEvent(event) {
        if (!(event.type in this.listeners)) {
          return;
        }

        var stack = this.listeners[event.type];
        var stackToCall = stack.slice();

        for (var i = 0, l = stackToCall.length; i < l; i++) {
          var listener = stackToCall[i];

          try {
            listener.callback.call(this, event);
          } catch (e) {
            Promise.resolve().then(function () {
              throw e;
            });
          }

          if (listener.options && listener.options.once) {
            this.removeEventListener(event.type, listener.callback);
          }
        }

        return !event.defaultPrevented;
      }
    }]);

    return Emitter;
  }();

  var AbortSignal = /*#__PURE__*/function (_Emitter) {
    _inherits(AbortSignal, _Emitter);

    var _super = _createSuper(AbortSignal);

    function AbortSignal() {
      var _this;

      _classCallCheck(this, AbortSignal);

      _this = _super.call(this); // Some versions of babel does not transpile super() correctly for IE <= 10, if the parent
      // constructor has failed to run, then "this.listeners" will still be undefined and then we call
      // the parent constructor directly instead as a workaround. For general details, see babel bug:
      // https://github.com/babel/babel/issues/3041
      // This hack was added as a fix for the issue described here:
      // https://github.com/Financial-Times/polyfill-library/pull/59#issuecomment-477558042

      if (!_this.listeners) {
        Emitter.call(_assertThisInitialized(_this));
      } // Compared to assignment, Object.defineProperty makes properties non-enumerable by default and
      // we want Object.keys(new AbortController().signal) to be [] for compat with the native impl


      Object.defineProperty(_assertThisInitialized(_this), 'aborted', {
        value: false,
        writable: true,
        configurable: true
      });
      Object.defineProperty(_assertThisInitialized(_this), 'onabort', {
        value: null,
        writable: true,
        configurable: true
      });
      return _this;
    }

    _createClass(AbortSignal, [{
      key: "toString",
      value: function toString() {
        return '[object AbortSignal]';
      }
    }, {
      key: "dispatchEvent",
      value: function dispatchEvent(event) {
        if (event.type === 'abort') {
          this.aborted = true;

          if (typeof this.onabort === 'function') {
            this.onabort.call(this, event);
          }
        }

        _get(_getPrototypeOf(AbortSignal.prototype), "dispatchEvent", this).call(this, event);
      }
    }]);

    return AbortSignal;
  }(Emitter);
  var AbortController = /*#__PURE__*/function () {
    function AbortController() {
      _classCallCheck(this, AbortController);

      // Compared to assignment, Object.defineProperty makes properties non-enumerable by default and
      // we want Object.keys(new AbortController()) to be [] for compat with the native impl
      Object.defineProperty(this, 'signal', {
        value: new AbortSignal(),
        writable: true,
        configurable: true
      });
    }

    _createClass(AbortController, [{
      key: "abort",
      value: function abort() {
        var event;

        try {
          event = new Event('abort');
        } catch (e) {
          if (typeof document !== 'undefined') {
            if (!document.createEvent) {
              // For Internet Explorer 8:
              event = document.createEventObject();
              event.type = 'abort';
            } else {
              // For Internet Explorer 11:
              event = document.createEvent('Event');
              event.initEvent('abort', false, false);
            }
          } else {
            // Fallback where document isn't available:
            event = {
              type: 'abort',
              bubbles: false,
              cancelable: false
            };
          }
        }

        this.signal.dispatchEvent(event);
      }
    }, {
      key: "toString",
      value: function toString() {
        return '[object AbortController]';
      }
    }]);

    return AbortController;
  }();

  if (typeof Symbol !== 'undefined' && Symbol.toStringTag) {
    // These are necessary to make sure that we get correct output for:
    // Object.prototype.toString.call(new AbortController())
    AbortController.prototype[Symbol.toStringTag] = 'AbortController';
    AbortSignal.prototype[Symbol.toStringTag] = 'AbortSignal';
  }

  function polyfillNeeded(self) {
    if (self.__FORCE_INSTALL_ABORTCONTROLLER_POLYFILL) {
      console.log('__FORCE_INSTALL_ABORTCONTROLLER_POLYFILL=true is set, will force install polyfill');
      return true;
    } // Note that the "unfetch" minimal fetch polyfill defines fetch() without
    // defining window.Request, and this polyfill need to work on top of unfetch
    // so the below feature detection needs the !self.AbortController part.
    // The Request.prototype check is also needed because Safari versions 11.1.2
    // up to and including 12.1.x has a window.AbortController present but still
    // does NOT correctly implement abortable fetch:
    // https://bugs.webkit.org/show_bug.cgi?id=174980#c2


    return typeof self.Request === 'function' && !self.Request.prototype.hasOwnProperty('signal') || !self.AbortController;
  }

  /**
   * Note: the "fetch.Request" default value is available for fetch imported from
   * the "node-fetch" package and not in browsers. This is OK since browsers
   * will be importing umd-polyfill.js from that path "self" is passed the
   * decorator so the default value will not be used (because browsers that define
   * fetch also has Request). One quirky setup where self.fetch exists but
   * self.Request does not is when the "unfetch" minimal fetch polyfill is used
   * on top of IE11; for this case the browser will try to use the fetch.Request
   * default value which in turn will be undefined but then then "if (Request)"
   * will ensure that you get a patched fetch but still no Request (as expected).
   * @param {fetch, Request = fetch.Request}
   * @returns {fetch: abortableFetch, Request: AbortableRequest}
   */

  function abortableFetchDecorator(patchTargets) {
    if ('function' === typeof patchTargets) {
      patchTargets = {
        fetch: patchTargets
      };
    }

    var _patchTargets = patchTargets,
        fetch = _patchTargets.fetch,
        _patchTargets$Request = _patchTargets.Request,
        NativeRequest = _patchTargets$Request === void 0 ? fetch.Request : _patchTargets$Request,
        NativeAbortController = _patchTargets.AbortController,
        _patchTargets$__FORCE = _patchTargets.__FORCE_INSTALL_ABORTCONTROLLER_POLYFILL,
        __FORCE_INSTALL_ABORTCONTROLLER_POLYFILL = _patchTargets$__FORCE === void 0 ? false : _patchTargets$__FORCE;

    if (!polyfillNeeded({
      fetch: fetch,
      Request: NativeRequest,
      AbortController: NativeAbortController,
      __FORCE_INSTALL_ABORTCONTROLLER_POLYFILL: __FORCE_INSTALL_ABORTCONTROLLER_POLYFILL
    })) {
      return {
        fetch: fetch,
        Request: Request
      };
    }

    var Request = NativeRequest; // Note that the "unfetch" minimal fetch polyfill defines fetch() without
    // defining window.Request, and this polyfill need to work on top of unfetch
    // hence we only patch it if it's available. Also we don't patch it if signal
    // is already available on the Request prototype because in this case support
    // is present and the patching below can cause a crash since it assigns to
    // request.signal which is technically a read-only property. This latter error
    // happens when you run the main5.js node-fetch example in the repo
    // "abortcontroller-polyfill-examples". The exact error is:
    //   request.signal = init.signal;
    //   ^
    // TypeError: Cannot set property signal of #<Request> which has only a getter

    if (Request && !Request.prototype.hasOwnProperty('signal') || __FORCE_INSTALL_ABORTCONTROLLER_POLYFILL) {
      Request = function Request(input, init) {
        var signal;

        if (init && init.signal) {
          signal = init.signal; // Never pass init.signal to the native Request implementation when the polyfill has
          // been installed because if we're running on top of a browser with a
          // working native AbortController (i.e. the polyfill was installed due to
          // __FORCE_INSTALL_ABORTCONTROLLER_POLYFILL being set), then passing our
          // fake AbortSignal to the native fetch will trigger:
          // TypeError: Failed to construct 'Request': member signal is not of type AbortSignal.

          delete init.signal;
        }

        var request = new NativeRequest(input, init);

        if (signal) {
          Object.defineProperty(request, 'signal', {
            writable: false,
            enumerable: false,
            configurable: true,
            value: signal
          });
        }

        return request;
      };

      Request.prototype = NativeRequest.prototype;
    }

    var realFetch = fetch;

    var abortableFetch = function abortableFetch(input, init) {
      var signal = Request && Request.prototype.isPrototypeOf(input) ? input.signal : init ? init.signal : undefined;

      if (signal) {
        var abortError;

        try {
          abortError = new DOMException('Aborted', 'AbortError');
        } catch (err) {
          // IE 11 does not support calling the DOMException constructor, use a
          // regular error object on it instead.
          abortError = new Error('Aborted');
          abortError.name = 'AbortError';
        } // Return early if already aborted, thus avoiding making an HTTP request


        if (signal.aborted) {
          return Promise.reject(abortError);
        } // Turn an event into a promise, reject it once `abort` is dispatched


        var cancellation = new Promise(function (_, reject) {
          signal.addEventListener('abort', function () {
            return reject(abortError);
          }, {
            once: true
          });
        });

        if (init && init.signal) {
          // Never pass .signal to the native implementation when the polyfill has
          // been installed because if we're running on top of a browser with a
          // working native AbortController (i.e. the polyfill was installed due to
          // __FORCE_INSTALL_ABORTCONTROLLER_POLYFILL being set), then passing our
          // fake AbortSignal to the native fetch will trigger:
          // TypeError: Failed to execute 'fetch' on 'Window': member signal is not of type AbortSignal.
          delete init.signal;
        } // Return the fastest promise (don't need to wait for request to finish)


        return Promise.race([cancellation, realFetch(input, init)]);
      }

      return realFetch(input, init);
    };

    return {
      fetch: abortableFetch,
      Request: Request
    };
  }

  (function (self) {

    if (!polyfillNeeded(self)) {
      return;
    }

    if (!self.fetch) {
      console.warn('fetch() is not available, cannot install abortcontroller-polyfill');
      return;
    }

    var _abortableFetch = abortableFetchDecorator(self),
        fetch = _abortableFetch.fetch,
        Request = _abortableFetch.Request;

    self.fetch = fetch;
    self.Request = Request;
    Object.defineProperty(self, 'AbortController', {
      writable: true,
      enumerable: false,
      configurable: true,
      value: AbortController
    });
    Object.defineProperty(self, 'AbortSignal', {
      writable: true,
      enumerable: false,
      configurable: true,
      value: AbortSignal
    });
  })(typeof self !== 'undefined' ? self : global);

})));