JavaScript file to parse login time

parseLoginTime.js

// from API or anywhere
const dateString = "2018-05-20 08:06:12";

// add plural to string (hour -> hours) if val > 1
function formatLoginTime(val, str) {
  return (val.toString() + ' ' + ((val > "1") ? str : str.slice(0, -1)));
}

// pastTime - currentTime
function getDeltaTime(str) {
  return (Math.abs(Date.parse(str) - (new Date).getTime()) / 1000);
}

// Source: https://stackoverflow.com/a/13904120
function parseLoginTime(dateString) {
  var delta, days, hours, minutes, seconds = null;

  delta = getDeltaTime(dateString);
  days = Math.floor(delta / 86400);
  delta -= days * 86400;
  hours = Math.floor(delta / 3600) % 24;
  delta -= hours * 3600;
  minutes = Math.floor(delta / 60) % 60;
  delta -= minutes * 60;
  seconds = delta % 60;
  if (days != "0") {
    loginTime = formatLoginTime(days, "days");
  }
  else if (hours != "0") {
    loginTime = formatLoginTime(hours, "hours");
  }
  else if (minutes != "0") {
    loginTime = formatLoginTime(minutes, "minutes");
  }
  else if (seconds != "0") {
    loginTime = formatLoginTime(seconds, "seconds");
  }
  return (loginTime + " ago")
}

console.log("Before: " + dateString)
console.log("After: " + parseLoginTime(dateString));