higher-order-reducers/lib/merge.js

A library of simple everyday reducer utility functions

'use strict';

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

var _isPlainObject = require('is-plain-object');

var _isPlainObject2 = _interopRequireDefault(_isPlainObject);

var _objectAssign = require('object-assign');

var _objectAssign2 = _interopRequireDefault(_objectAssign);

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

var merge = function merge(reducer) {
  if (typeof reducer !== 'function') {
    throw new Error('Argument supplied to `merge` is not a reducer');
  }

  return function (state, action) {
    if (!(0, _isPlainObject2.default)(state)) {
      throw new Error('`merge` only works with plain object states');
    }
    var nextState = reducer(state, action);
    if (!(0, _isPlainObject2.default)(nextState)) {
      throw new Error('The reducer in `merge` did not return a plain object');
    }
    return (0, _objectAssign2.default)({}, state, nextState);
  };
};

exports.default = merge;