bendc

// Imperative style
const createDivs = num => {
  for (var i = 0; i < num; i++)
    document.body.insertAdjacentHTML("beforeend", "<div></div>");
};
createDivs(10);


// Functional style: recursion
const createDivs = num => {

bendc

// ease-in

const easeInQuad = (t, b, c, d) =>
  c*(t/=d)*t + b;

const easeInCubic = (t, b, c, d) =>
  c*(t/=d)*t*t + b;

const easeInQuart = (t, b, c, d) =>
  c*(t/=d)*t*t*t + b;

bendc

const toRGB = (() => {
  const expand = hex =>
    hex.length < 7 ? hex.split("").reduce((a, b) => a + b + b) : hex;
  const convert = hex =>
    hex.match(/[\d\w]{2}/g).map(val => parseInt(val, 16));
  return hex => {
    const [r, g, b] = convert(expand(hex));
    return `rgb(${r}, ${g}, ${b})`;
  };
})();

bendc

const loop = (() => {
  const recur = (callback, count, i=0) => {
    if (i == count-1) return callback(i);
    callback(i);
    return recur(callback, count, i+1);
  };
  return (callback, count) => {
    if (count > 0) return recur(callback, count);
  };
})();

bendc

const cloneSet = (() =>
  new Set(new Set().add(1)).has(1)
  ? set => new Set(set)
  : set => {
    const clone = new Set();
    set.forEach(item => clone.add(item));
    return clone;
  })();

bendc

const arr = [["foo", "bar"], ["hello", "world"]];

// Create object from array of tuples
const obj = {}; arr.forEach(el => obj[el[0]] = el[1]);
const map = new Map(arr);

// Get object size
const objSize = Object.keys(obj).length;
const mapSize = map.size;

bendc

const isNumber = x =>
  !Number.isNaN(parseInt(x)) && Number.isInteger(Math.trunc(x));

bendc

const set = new Set(["foo", "bar"]);

const iterate = iterator => {
  const iteration = iterator.next();
  if (iteration.done) return;
  console.log(iteration.value);
  return iterate(iterator);
};

iterate(set.values()); // => foo, bar

bendc

const fib = (n, seq = [0, 1]) =>
  n - 2 ? fib(n - 1, [...seq, seq.slice(-2).reduce((a, b) => a + b)]) : seq;

fib(10); // 0, 1, 1, 2, 3, 5, 8, 13, 21, 34

bendc

const toMap = (() => {
  const convert = (obj, map = new Map(), keys = Object.keys(obj).values()) => {
    const state = keys.next();
    if (state.done) return map;
    const key = state.value;
    map.set(key, obj[key]);
    return convert(obj, map, keys);
  };
  return obj => obj instanceof Map ? obj : convert(obj);
})();