@storybook/channels/dist/esm/index.js

Storybook Channel is similar to an EventEmitter. Channels are used with Storybook implementations to send/receive events between the Storybook Manager and the Storybook Renderer.

import "core-js/modules/es.object.freeze.js";

var _templateObject;

function _taggedTemplateLiteral(strings, raw) { if (!raw) { raw = strings.slice(0); } return Object.freeze(Object.defineProperties(strings, { raw: { value: Object.freeze(raw) } })); }

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); Object.defineProperty(Constructor, "prototype", { writable: false }); return Constructor; }

import "core-js/modules/es.array.slice.js";
import "core-js/modules/es.object.to-string.js";
import "core-js/modules/es.regexp.to-string.js";
import "core-js/modules/web.immediate.js";
import "core-js/modules/es.object.keys.js";
import "core-js/modules/es.array.filter.js";
import "core-js/modules/web.dom-collections.for-each.js";
import deprecate from 'util-deprecate';
import dedent from 'ts-dedent';

var generateRandomId = function generateRandomId() {
  // generates a random 13 character string
  return Math.random().toString(16).slice(2);
};

export var Channel = /*#__PURE__*/function () {
  function Channel() {
    var _this = this;

    var _ref = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {},
        transport = _ref.transport,
        _ref$async = _ref.async,
        async = _ref$async === void 0 ? false : _ref$async;

    _classCallCheck(this, Channel);

    this.isAsync = void 0;
    this.sender = generateRandomId();
    this.events = {};
    this.data = {};
    this.transport = void 0;
    this.addPeerListener = deprecate(function (eventName, listener) {
      _this.addListener(eventName, listener);
    }, dedent(_templateObject || (_templateObject = _taggedTemplateLiteral(["\n      channel.addPeerListener is deprecated\n    "]))));
    this.isAsync = async;

    if (transport) {
      this.transport = transport;
      this.transport.setHandler(function (event) {
        return _this.handleEvent(event);
      });
    }
  }

  _createClass(Channel, [{
    key: "hasTransport",
    get: function get() {
      return !!this.transport;
    }
  }, {
    key: "addListener",
    value: function addListener(eventName, listener) {
      this.events[eventName] = this.events[eventName] || [];
      this.events[eventName].push(listener);
    }
  }, {
    key: "emit",
    value: function emit(eventName) {
      var _this2 = this;

      for (var _len = arguments.length, args = new Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
        args[_key - 1] = arguments[_key];
      }

      var event = {
        type: eventName,
        args: args,
        from: this.sender
      };
      var options = {};

      if (args.length >= 1 && args[0] && args[0].options) {
        options = args[0].options;
      }

      var handler = function handler() {
        if (_this2.transport) {
          _this2.transport.send(event, options);
        }

        _this2.handleEvent(event);
      };

      if (this.isAsync) {
        // todo I'm not sure how to test this
        setImmediate(handler);
      } else {
        handler();
      }
    }
  }, {
    key: "last",
    value: function last(eventName) {
      return this.data[eventName];
    }
  }, {
    key: "eventNames",
    value: function eventNames() {
      return Object.keys(this.events);
    }
  }, {
    key: "listenerCount",
    value: function listenerCount(eventName) {
      var listeners = this.listeners(eventName);
      return listeners ? listeners.length : 0;
    }
  }, {
    key: "listeners",
    value: function listeners(eventName) {
      var listeners = this.events[eventName];
      return listeners || undefined;
    }
  }, {
    key: "once",
    value: function once(eventName, listener) {
      var onceListener = this.onceListener(eventName, listener);
      this.addListener(eventName, onceListener);
    }
  }, {
    key: "removeAllListeners",
    value: function removeAllListeners(eventName) {
      if (!eventName) {
        this.events = {};
      } else if (this.events[eventName]) {
        delete this.events[eventName];
      }
    }
  }, {
    key: "removeListener",
    value: function removeListener(eventName, listener) {
      var listeners = this.listeners(eventName);

      if (listeners) {
        this.events[eventName] = listeners.filter(function (l) {
          return l !== listener;
        });
      }
    }
  }, {
    key: "on",
    value: function on(eventName, listener) {
      this.addListener(eventName, listener);
    }
  }, {
    key: "off",
    value: function off(eventName, listener) {
      this.removeListener(eventName, listener);
    }
  }, {
    key: "handleEvent",
    value: function handleEvent(event) {
      var listeners = this.listeners(event.type);

      if (listeners && listeners.length) {
        listeners.forEach(function (fn) {
          fn.apply(event, event.args);
        });
      }

      this.data[event.type] = event.args;
    }
  }, {
    key: "onceListener",
    value: function onceListener(eventName, listener) {
      var _this3 = this;

      var onceListener = function onceListener() {
        _this3.removeListener(eventName, onceListener);

        return listener.apply(void 0, arguments);
      };

      return onceListener;
    }
  }]);

  return Channel;
}();
export default Channel;