kilto/lib/createStore.js

A state management system with easy async and low boilerplate.

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = createStore;

var _isPromise = require('./util/isPromise');

var _isPromise2 = _interopRequireDefault(_isPromise);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

// TODO: middleware support

function createStore(initialState) {
  var state = initialState;
  var subscribers = [];

  var getState = function getState() {
    return state;
  };

  var updateState = function updateState(newState) {
    if (newState === state) return state;
    state = newState;

    subscribers.forEach(function (subscriber) {
      subscriber(state);
    });

    return state;
  };

  var unsubscribe = function unsubscribe(cb) {
    var i = subscribers.indexOf(cb);
    if (i > -1) {
      subscribers.splice(i, 1);
    }
  };

  var subscribe = function subscribe(cb) {
    subscribers.push(cb);
    return function () {
      return unsubscribe(cb);
    };
  };

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

    if (actionsArg === null || actionsArg === undefined) {
      throw new TypeError('The first argument of dispatch must be a function or array.');
    }
    var actions = Array.isArray(actionsArg) ? actionsArg : [actionsArg];
    var action = actions[0];

    var result = action.apply(undefined, [state].concat(args));

    if (actions.length > 1) {
      if ((0, _isPromise2.default)(result)) {
        result.then(function (asyncResult) {
          dispatch.apply(undefined, [actions.slice(1), asyncResult].concat(args));
        }).catch(function (error) {
          console.error('Error encountered in action promise. Action was ignored.', error, action.name);
        });
      } else {
        dispatch.apply(undefined, [actions.slice(1), result].concat(args));
      }
    } else {
      if ((0, _isPromise2.default)(result) || result === null || result === undefined) {
        throw new Error('The last function in an action must be a syncrounous pure function of state (not a Promise)! Offending action is ' + action.name + '.');
      }
      updateState(result);
    }
  };

  var reset = function reset() {
    return updateState(initialState);
  };

  return { getState: getState, subscribe: subscribe, reset: reset, dispatch: dispatch };
}