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

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);