2020 Advent of Code Day 02 Part One Solution in JavaScript

advent-of-code-2020_day02_part-one.js

String.prototype.count = function(char) { 
    return (this.length - this.replace(new RegExp(char,"g"), '').length) / s1.length
}

input.reduce((accum, item) => {
  const charMin = item[0].split('-')[0]
  const charMax = item[0].split('-')[1]
  const char = item[1]
  const password = item[2]

  const charCount = password.count(char)
  if (charCount <= charMax && charCount >= charMin) {
    accum++
  }
  return accum
}, 0)