Object.assign({}, object1, object2, {prop: value});


const newObject = {
  ...object1,
  ...object2,
  prop: value,
}

newObject === object1 // false
newObject[obj1OnlyProp] === object1[obj1OnlyProp] // true !

const state = {
  sets: [{
    id: 1,
    name: 'First set',
    locations: [{
      id: 1,
      setId: 1,
      name: 'First location',
      jobs: [{id: 1, locationId: 1, name: 'First job'}, {id: 2, locationId: 1, name: 'Second job'}]
    }, {
      id: 2,
      setId: 1,
      name: 'Second location',
      jobs: [{id: 3, locationId: 2, name: 'Third job'}, {id: 4, locationId: 2, name: 'Fourth job'}]
    }]
  }, {
    id: 2,
    name: 'Second set',
    locations: [{
      id: 3,
      setId: 2,
      name: 'Third location',
      jobs: [{id: 5, locationId: 3, name: 'Fifth job'}, {id: 6, locationId: 3, name: 'Sixth job'}]
    }, {
      id: 4,
      setId: 2,
      name: 'Fourth location',
      jobs: [{id: 7, locationId: 4, name: 'Seventh job'}, {id: 8, locationId: 4, name: 'Eighth job'}]
    }]
  }]
};

const normalizedState = {
  sets: {
    1: {
      id: 1,
      name: 'First set',
      locations: [1, 2]
    },
    2: {
      id: 2,
      name: 'Second set',
      locations: [3, 4]
    }
  },
  locations: {
    1: {
      id: 1,
      setId: 1,
      name: 'First location',
      jobs: [1, 2]
    },
    2: {
      id: 2,
      setId: 1,
      name: 'Second location',
      jobs: [3, 4]
    },

    ....
  },
  jobs: {
    1: {
      id: 1,
      locationId: 1,
      name: 'First job'
    },
    2: {
      id: 2,
      locationId: 1,
      name: 'Second job'
    },

    ...
  }
};

function updateSet(state, payload) {
  return {
    ...state,
    sets: {
      ...state.sets,
      [payload.id]: {
        ...state.sets[payload.id],
        ...payload
      }
    }
  }
}

function updateSet(state, payload) {
  return {
    ...state,
    sets: {
      ...state.sets,
      [payload.id]: {
        ...state.sets[payload.id],
        ...payload
      }
    }
  }
}


function updateLocation(state, payload) {
  ...
  return updateSet(updatedState, set);
}


function updateJob(state, payload) {
  const job = state.jobs[payload.id];
  const location = state.locations[job.locationId];

  return updateLocation({
    ...state,
    jobs: {
      ...state.jobs,
      [payload.id]: {
        ...job,
        ...payload
      }
    }
  }, location);
}

function updateJobs(state, payload: any[]) {
  let tempState= state;

  payload.forEach(jobPayload => {
    const job = state.jobs[jobPayload.id];
    const location = state.locations[job.locationId];

    tempState = updateLocations({
      ...state,
      jobs: {
        ...state.jobs,
        [jobPayload.id]: {
          ...job,
          ...jobPayload
        }
      }
    }, [location]);
  });

  return tempState;
}

function updateJobs(state, payload: any[]) {
  const jobs = {};
  const locations = {};

  payload.forEach(jobPayload => {
    const job = state.jobs[jobPayload.id];
    locations[job.locationId] = locations[job.locationId] || state.locations[job.locationId];

    jobs[jobPayload.id] = {
      ...job,
      ...jobPayload
    }
  });

  return updateLocations({
    ...state,
    jobs: {
      ...state.jobs,
      ...jobs
    }
  }, Object.keys(locations).map(id => locations[id]));
}

function updateJobs(state, payload: any[]) {
    const jobs = {};
    const locations = {};

    payload.forEach(jobPayload => {
        const job = state.jobs[jobPayload.id];
        locations[job.locationId] = locations[job.locationId] || state.locations[job.locationId];

        jobs[jobPayload.id] = {
            ...job,
            ...jobPayload
        }
    });

    return updateLocations({
        ...state,
        jobs: {
            ...state.jobs,
            byId: {
                ...state.jobs.byId,
                ...jobs
            }
        }
    }, Object.keys(locations).map(id => locations[id]));
}

function splitReducers(state: CalendarData, action): CalendarData {
    return combineReducers({
        jobs
    });
}

function jobs(state: {allIds: number[], byId: {[id: number]: CalendarJob}}, action) {
    return combineReducers({
        byId: jobsById,
        allIds: jobsAllIds
    });
}

function jobsById(state: {[id: number]: CalendarJob}, action): {[id: number]: CalendarJob} {
    switch (action.type) {
        case UPDATE_JOBS:
            return updateJobs(state, action);
        default:
            return state;
    }
}

function updateJobs(state: {[id: number]: CalendarJob}, action): {[id: number]: CalendarJob} {
    const jobs = {};

    payload.forEach(jobPayload => {
        jobs[jobPayload.id] = {
            ...state.jobs[jobPayload.id],
            ...jobPayload
        }
    });

    return {
        ...state,
        ...jobs
    }
}