goofballLogic

function resolvePath(fs, path) {
  if (!(path in fs)) return null;
  const { [path]: nextPath, ...others } = fs;
  return nextPath ? resolvePath(others, nextPath) : path;
}

goofballLogic

const resolvePath = (fs, path, ...visited) => 
  visited.includes(path)
    ? null
    : fs[path]
      ? resolvePath(fs, fs[path], path, ...visited)
      : path
    ;

goofballLogic

const swap = (xs, n, i) =>
    xs.fill(
        xs.splice(i+1, 1, n)[0],
        i,
        i+1
    )
;

const chase = (xs, n, i) =>
    i === xs.length - 1

goofballLogic

// thanks: https://stackoverflow.com/a/16353241
const isLeapYear = year => 
    (
        // divisible by 4 but not 100
        (year % 4 == 0) && (year % 100 != 0)
    ) || (
        // divisible by 400
        year % 400 == 0
    );

goofballLogic

const flippedy = str => 
    str
        ?.split(" ")
        .map(word => [
            word.match(/[aeiou]/gi)?.length || 0,
            word
        ])
        .reduce((a, word, i) => 
            i
                ? [

goofballLogic

const hungryBears = bears =>
    bears
      .map(x => ({ ...x })) // avoid tainting the inputs
      .sort((a, b) =>
        (a.visited = a.visited || (bears.sum = (bears.sum || 0) + a.hunger) || true)
            &&
        (b.visited = b.visited || (bears.sum = (bears.sum || 0) + b.hunger) || true)
            &&
        (a.name > b.name ? 1 : a.name < b.name ? -1 : 0))
      .filter(b => b.hunger > bears.sum / bears.length)

goofballLogic

const replaceRepeats = (input, number) => 
    input.replaceAll(
        new RegExp(`${number}+`, "g"), 
        x => x.length);

// test

[
    replaceRepeats('1234500362000440', 0) === "1234523623441",
    replaceRepeats('000000000000', 0) == "12",

goofballLogic

/* solution */

const validate = ([y, z, ...rest]) =>
    rest.length
        ? (rest.shift() === y && validate([z, y, ...rest]))
        : true;



/* testing */

goofballLogic

/* solution */

function process([y, z, ...rest] = []) {
    while (rest.length) {
        if (rest.shift() !== y) return false;
        [z, y] = [y, z];
    }
    return true;
}    

goofballLogic

const rotate = ([ head, ...tail]) => [...tail, head];
const explode = (num, acc = []) => 
    num === 0 ? acc 
    : explode(num - 1, [num, ...acc])
    ; 
const build = (num, input, lines = []) => 
    num === 0 ? lines 
    : build(num - 1, rotate(input), [...lines, input])
    ;