balanceValidator.js

var input = process.argv[2]

var matcher = { 41: 40, 93: 91, 125: 123 }
var tracker = []

input.split('').forEach(function(symbol) {
  var code = symbol.charCodeAt(0)
  if (code === 40 || code === 91 || code === 123) {
    tracker.push(code)
  } else if (code === 41 || code === 93 || code === 125) {
    tracker[tracker.length - 1] === matcher[code] ? tracker.pop() : tracker.push('Err')
  }
})

console.log(tracker.length < 1)

boom