amsterdamharu

const createSelectObservable = (() => {
  let state;
  let pReducer = (state, action) => state;
  const subscribers = new Map();
  const addSubscriber = (selector) => {
    subscribers.set(selector, selector);
    //return unsubscribe function
    return () => subscribers.delete(selector);
  };
  const dispatch = (action) => {

amsterdamharu

const REPLACED = 'REPLACED';
const last = (fn) => {
  const current = { value: {} };
  return (...args) => {
    const now = {};
    current.value = now;
    return Promise.resolve(args)
      .then((args) => fn(...args))
      .then((resolve) =>
        current.value === now

amsterdamharu

import React from 'react';
import ReactDOM from 'react-dom';
//for Stack overflow snippet that doesn't allow imports
const { useRef, useState } = React;

const compose = (...fns) =>
  fns.reduce((result, fn) => (...args) =>
    fn(result(...args))
  );
const mw = () => (next) => (action) => next(action);

amsterdamharu

//using partially applied functions (closures) are used for sorting to
//  demonstrate how to prevent duplicate implementation and writing
//  imperative code. Most of your code should express "what it does"
//  not "how it does it"
const data1 = [
  { id: 1, name: 'a', items: [1, 2, 3] },
  { id: 2, name: 'a', items: [1, 2] },
  { id: 3, name: 'b', items: [4, 5] },
  { id: 4, name: 'b', items: [4, 5, 6, 7] },
];

amsterdamharu

//group promise returning function
const createGroup = (cache) => (
  fn,
  getKey = (...x) => JSON.stringify(x)
) => (...args) => {
  const key = getKey(args);
  let result = cache.get(key);
  if (result) {
    return result;
  }

amsterdamharu

import React from 'react';
import ReactDOM from 'react-dom';

const useContainer = (props, container) => {
  return container(props);
};
const Counter = ({ counter, up }) => {
  const r = React.useRef(0);
  r.current++;
  return (

amsterdamharu

import React from 'react';
import ReactDOM from 'react-dom';
import * as Reselect from 'reselect';

const {
  useMemo,
  useState,
  useContext,
  useRef,
  useCallback,

amsterdamharu

<!-- begin snippet: js hide: false console: true babel: true -->

<!-- language: lang-js -->
    import * as React from 'react';
    import ReactDOM from 'react-dom';
    import * as Redux from 'redux';
    import * as ReactRedux from 'react-redux';
    import * as Reselect from 'reselect';
    import * as immer from 'immer';

amsterdamharu

import React from 'react';
export const NOT_REQUESTED = {
  requested: false,
  loading: false,
};
const AVAILABLE = {
  requested: true,
  loading: false,
};
const isResult = (value) =>

amsterdamharu

const state = {
  people: {
    1: { id: 1, name: 'one' },
    2: { id: 2, name: 'two' },
    3: { id: 3, name: 'three' },
  },
  likes: {
    1: [2, 3],
    2: [1],
    3: [1],