reedx/src/utils/createSelectors.js

Like redux but with less code

import isFunc from './isFunc'
import reduce from './reduce'

const { assign, keys } = Object

const isObject = (obj) => obj === Object(obj)
const isNull = (obj) => !obj && !isObject(obj)

const isPrimitive = (state) =>
  isNull(state) || (!isObject(state) && !isFunc(state))

const hasGetter = (prop) =>
  prop && prop.get && isFunc(prop.get)

export const getInState = (state, key) =>
  hasGetter(state) ? state.get(key) : isObject(state) ? state[key] : state

const stateAsProp = (name) => ({
  [name]: (state) => getInState(state, name)
})

const createSelector = (name, key) => (state) =>
  getInState(getInState(state, name), key)

const reduceState = (keys) => (name) =>
  reduce(keys, (obj, key) => assign(obj, { [key]: createSelector(name, key) }), {})

const getMapKeys = (state) =>
  hasGetter(state) ? [...state.keys()] : keys(state)

const createSelectors = (name, { state, computed }) => {
  if (isPrimitive(state)) return stateAsProp(name)

  return assign(reduceState(getMapKeys(state))(name), computed || null)
}

export default createSelectors