coopgo/node_modules/consolidated-events/lib/index.esm.js

var CAN_USE_DOM = !!(typeof window !== 'undefined' && window.document && window.document.createElement);

// Adapted from Modernizr
// https://github.com/Modernizr/Modernizr/blob/acb3f0d9/feature-detects/dom/passiveeventlisteners.js#L26-L37
function testPassiveEventListeners() {
  if (!CAN_USE_DOM) {
    return false;
  }

  if (!window.addEventListener || !window.removeEventListener || !Object.defineProperty) {
    return false;
  }

  var supportsPassiveOption = false;
  try {
    var opts = Object.defineProperty({}, 'passive', {
      // eslint-disable-next-line getter-return
      get: function () {
        function get() {
          supportsPassiveOption = true;
        }

        return get;
      }()
    });
    var noop = function noop() {};
    window.addEventListener('testPassiveEventSupport', noop, opts);
    window.removeEventListener('testPassiveEventSupport', noop, opts);
  } catch (e) {
    // do nothing
  }

  return supportsPassiveOption;
}

var memoized = void 0;

function canUsePassiveEventListeners() {
  if (memoized === undefined) {
    memoized = testPassiveEventListeners();
  }
  return memoized;
}

function normalizeEventOptions(eventOptions) {
  if (!eventOptions) {
    return undefined;
  }

  if (!canUsePassiveEventListeners()) {
    // If the browser does not support the passive option, then it is expecting
    // a boolean for the options argument to specify whether it should use
    // capture or not. In more modern browsers, this is passed via the `capture`
    // option, so let's just hoist that value up.
    return !!eventOptions.capture;
  }

  return eventOptions;
}

/* eslint-disable no-bitwise */

/**
 * Generate a unique key for any set of event options
 */
function eventOptionsKey(normalizedEventOptions) {
  if (!normalizedEventOptions) {
    return 0;
  }

  // If the browser does not support passive event listeners, the normalized
  // event options will be a boolean.
  if (normalizedEventOptions === true) {
    return 100;
  }

  // At this point, the browser supports passive event listeners, so we expect
  // the event options to be an object with possible properties of capture,
  // passive, and once.
  //
  // We want to consistently return the same value, regardless of the order of
  // these properties, so let's use binary maths to assign each property to a
  // bit, and then add those together (with an offset to account for the
  // booleans at the beginning of this function).
  var capture = normalizedEventOptions.capture << 0;
  var passive = normalizedEventOptions.passive << 1;
  var once = normalizedEventOptions.once << 2;
  return capture + passive + once;
}

function ensureCanMutateNextEventHandlers(eventHandlers) {
  if (eventHandlers.handlers === eventHandlers.nextHandlers) {
    // eslint-disable-next-line no-param-reassign
    eventHandlers.nextHandlers = eventHandlers.handlers.slice();
  }
}

function TargetEventHandlers(target) {
  this.target = target;
  this.events = {};
}

TargetEventHandlers.prototype.getEventHandlers = function () {
  function getEventHandlers(eventName, options) {
    var key = String(eventName) + ' ' + String(eventOptionsKey(options));

    if (!this.events[key]) {
      this.events[key] = {
        handlers: [],
        handleEvent: undefined
      };
      this.events[key].nextHandlers = this.events[key].handlers;
    }

    return this.events[key];
  }

  return getEventHandlers;
}();

TargetEventHandlers.prototype.handleEvent = function () {
  function handleEvent(eventName, options, event) {
    var eventHandlers = this.getEventHandlers(eventName, options);
    eventHandlers.handlers = eventHandlers.nextHandlers;
    eventHandlers.handlers.forEach(function (handler) {
      if (handler) {
        // We need to check for presence here because a handler function may
        // cause later handlers to get removed. This can happen if you for
        // instance have a waypoint that unmounts another waypoint as part of an
        // onEnter/onLeave handler.
        handler(event);
      }
    });
  }

  return handleEvent;
}();

TargetEventHandlers.prototype.add = function () {
  function add(eventName, listener, options) {
    var _this = this;

    // options has already been normalized at this point.
    var eventHandlers = this.getEventHandlers(eventName, options);

    ensureCanMutateNextEventHandlers(eventHandlers);

    if (eventHandlers.nextHandlers.length === 0) {
      eventHandlers.handleEvent = this.handleEvent.bind(this, eventName, options);

      this.target.addEventListener(eventName, eventHandlers.handleEvent, options);
    }

    eventHandlers.nextHandlers.push(listener);

    var isSubscribed = true;
    var unsubscribe = function () {
      function unsubscribe() {
        if (!isSubscribed) {
          return;
        }

        isSubscribed = false;

        ensureCanMutateNextEventHandlers(eventHandlers);
        var index = eventHandlers.nextHandlers.indexOf(listener);
        eventHandlers.nextHandlers.splice(index, 1);

        if (eventHandlers.nextHandlers.length === 0) {
          // All event handlers have been removed, so we want to remove the event
          // listener from the target node.

          if (_this.target) {
            // There can be a race condition where the target may no longer exist
            // when this function is called, e.g. when a React component is
            // unmounting. Guarding against this prevents the following error:
            //
            //   Cannot read property 'removeEventListener' of undefined
            _this.target.removeEventListener(eventName, eventHandlers.handleEvent, options);
          }

          eventHandlers.handleEvent = undefined;
        }
      }

      return unsubscribe;
    }();
    return unsubscribe;
  }

  return add;
}();

var EVENT_HANDLERS_KEY = '__consolidated_events_handlers__';

// eslint-disable-next-line import/prefer-default-export
function addEventListener(target, eventName, listener, options) {
  if (!target[EVENT_HANDLERS_KEY]) {
    // eslint-disable-next-line no-param-reassign
    target[EVENT_HANDLERS_KEY] = new TargetEventHandlers(target);
  }
  var normalizedEventOptions = normalizeEventOptions(options);
  return target[EVENT_HANDLERS_KEY].add(eventName, listener, normalizedEventOptions);
}

export { addEventListener };