Advent of Code - Day 1: Not Quite Lisp

aoc1.js

const parseFloor = (str) => {
  const floorCharFns = {
    '(': n => n + 1,
    ')': n => n - 1
  };
  let floor = 0;
  let error;
  let firstBasementPos;
  for (let i = 0; i < str.length; i++) {
    const char = str[i];
    const fn = floorCharFns[char];
    if (!fn) {
      error = `Invalid character ${char} at position ${i + 1}`;
    }
    floor = fn(floor);
    if (floor == -1 && !firstBasementPos) firstBasementPos = i + 1;
  }
  return {floor, error, firstBasementPos};
};

const expect = (actual, expected) => {
  if (actual !== expected) {
    console.error(`Expected ${expected} got ${actual}`)
    return false;
  }
  return true;
};

console.clear();

const tests = [
  ...[
    ['(())', 0],
    ['()()', 0],
    ['(((', 3],
    ['(()(()(', 3],
    ['))(((((', 3],
    ['())', -1],
    ['))(', -1],
    [')))', -3],
    [')())())', -3],
  ].map(([str, expected]) => {
    return expect(parseFloor(str).floor, expected);
  }),
  [
    [')', 1],
  	['()())', 5]
  ].map(([str, expected]) => {
    return expect(parseFloor(str).firstBasementPos, expected);
  })
];

if (tests.every(Boolean)) console.log('All tests passed!');