ConteoRegresivo.js

function getTime() {
  now = new Date();
  fecha = new Date("2017-10-30 00:00:00");
  diffDate = (fecha - now)
  
  months = diffDate / 1000 / 60 / 60 / 24 / 30;
  monthsRound = Math.floor(months);
  
  days          = diffDate / 1000 / 60 / 60 / 24 - (30 * monthsRound);
  daysAux       = diffDate / 1000 / 60 / 60 / 24;
  daysAuxRound  = Math.floor(daysAux);
  daysRound     = Math.floor(days);
  
  hours = diffDate / 1000 / 60 / 60 - (24 * daysAuxRound);
  hoursRound = Math.floor(hours);
  
  minutes = diffDate / 1000 /60 - (24 * 60 * daysAuxRound) - (60 * hoursRound);
  minutesRound = Math.floor(minutes);
  
  seconds = diffDate / 1000 - (24 * 60 * 60 * daysAuxRound) - (60 * 60 * hoursRound) - (60 * minutesRound);
  secondsRound = Math.round(seconds);
  
  if (daysRound <= "-1") {
    console.log('Fecha anterior a hoy')
  }
  else{
    // document.getElementById('dias').innerHTML = daysRound;
    // document.getElementById('horas').innerHTML = hoursRound;
    // document.getElementById('min').innerHTML = minutesRound;
    // document.getElementById('seg').innerHTML = secondsRound;
    console.log(`mes: ${monthsRound} - día: ${daysRound} - hora: ${hoursRound} - minuto: ${minutesRound} - segundo: ${secondsRound} `)
  }
}
window.setInterval(()=> getTime(), 1000);