advent-code-day-4.js

var ar = document.getElementsByTagName('pre')[0].textContent.split('\n\n').filter(Boolean)

function transform(str) {
  const a = str.replace(/\s/g, ' ').split(' ')
  
  return a.reduce((t, n) => {
    const [key, val] = n.split(':');
    t[key] = val;
    return t;
  }, {})
}

function validateHeight(s) {
  const h = parseInt(s);
  switch(true) {
    case /cm/.test(s):
      return h >= 150 && h <= 193;
    case /in/.test(s):
      return h >= 59 && h <= 76;
  };
}

function validateColor(s) {
  if (!s) return false
  const [,color] = s.split('#');
  if (!color) return false;
  
  return (
    color.length === 6 &&
    !/[^A-Za-z0-9]+/.test(color)
  )
}

function validateEcl(s) {
  return ['amb', 'blu', 'brn', 'gry', 'grn', 'hzl', 'oth'].includes(s);
}

function validateId(n) {
  if (!n) return false;
  return n.length === 9 && Number(n)
}

function validateRange(n, down, up) {
  const i = Number(n);  
  return i >= down && i <= up;
}

function validate(pass) {
  const { 
    byr,
    iyr,
    eyr,
    hgt,
    hcl,
    ecl,
    pid,
    cid,
  } = pass;
  return (
    validateRange(byr, 1920, 2002) &&
    validateRange(iyr, 2010, 2020) &&
    validateRange(eyr, 2020, 2030) &&
    validateHeight(hgt) &&
    validateColor(hcl) &&
    validateEcl(ecl) &&
    validateId(pid)
  )
}

ar.filter(Boolean).map(transform).filter(validate).length