tvler

type ActionTypes = 'actionA' | 'actionB' | 'actionC' | 'actionNoPayload';

type ActionPayloads = {
  actionA: { payload: number };
  actionB: { payload: string };
  actionC: { foo: boolean; bar: boolean };
};

type Actions = {
  [key in ActionTypes]: {

tvler

type DeepRequiredNonNullable<T> = T extends null | undefined
  ? never
  : (T extends (infer ElementType)[]
      ? DeepRequiredNonNullable<ElementType>[]
      : (T extends Record<string | number, any>
          ? { [key in keyof T]-?: DeepRequiredNonNullable<T[key]> }
          : T));

// Number test
type BadPrimitive = number | null | undefined | string;

tvler

// Thanks to eddmann.com/posts/cartesian-product-in-javascript

const cartesianProduct = (...sets) =>
  sets.reduce((sets, set) => sets.flatMap(x => set.map(y => [...x, y])), [[]]);

cartesianProduct(
  ['a', 'b', 'c'],
  ['x', 'y', 'z'],
);

tvler

// React hook that returns a new key 
// when its passed in value goes from false to true.
// Use this for resetting a child component, firing events, etc!
const useNewKey = bool => {
  const [key, setKey] = useState(bool ? 0 : 1);

  const newKey = Boolean(bool) === Boolean(key % 2) ? key + 1 : key;

  useEffect(() => {
    setKey(newKey);

tvler

const areUnsortedArraysEqual = (...arrs) => {
  const everyEqual = ([first, ...arr], isEqual) =>
    arr.every(item => isEqual(first, item));

  return (
    everyEqual(arrs, (first, arr) => arr.length === first.length) &&
    everyEqual(
      arrs.map(arr =>
        arr.reduce(
          (map, item) => map.set(item, (map.get(item) || 0) + 1),

tvler

Exclude file types
!*.snap, !*.test.jsx, !*.test.js

tvler

const getCircularArrayIndex = (i, { length }) => 
  (i % length + length) % length;

const testArray = new Array(5);

for (let i = -30; i < 31; i++) {
 console.log(i, getCircularArrayIndex(i, testArray))   
}

tvler

open -a Preview ~/Library/Messages/Attachments

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new URLSearchParams([...new FormData(ev.target)])

tvler

const getProxy = (target = {}, key) =>
  target[key] || (target[key] = new Proxy({}, { get: getProxy }));

const fillPick = (proxy, fn, fromObject = fn(proxy)) =>
  Object.assign(
    {},
    ...Object.entries(proxy).map(([key, value]) => ({
      [key]: Object.keys(value).length
        ? fillPick(value, fn, fromObject[key])
        : fromObject[key],