running.js

const arguments = [...process.argv];

const actualMiles = arguments[2];
const date = arguments[3];

function dayOfYear() {
  let now = new Date();
  if (date) {
    now = new Date(date);
  }
  var start = new Date(now.getFullYear(), 0, 0);
  var diff = now - start;
  var oneDay = 1000 * 60 * 60 * 24;
  return Math.floor(diff / oneDay);
}

function format(date, y) {
  var z = {
    M: date.getMonth() + 1,
    d: date.getDate(),
    h: date.getHours(),
    m: date.getMinutes(),
    s: date.getSeconds()
  };
  y = y.replace(/(M+|d+|h+|m+|s+)/g, function(v) {
    return ((v.length > 1 ? "0" : "") + eval("z." + v.slice(-1))).slice(-2);
  });

  return y.replace(/(y+)/g, function(v) {
    return date
      .getFullYear()
      .toString()
      .slice(-v.length);
  });
}

function dateFromDay(day) {
  var date = new Date(2020, 0); // initialize a date in `year-01-01`
  return format(new Date(date.setDate(day)), "MM/dd/yyyy"); // add the number of days
}

function milesPerDay() {
  // 2020 is a leap year!
  return 1000 / 366;
}

function goalForToday() {
  return milesPerDay() * dayOfYear();
}

function compareActualMiles() {
  if (!actualMiles) {
    return;
  }

  console.log(
    `Actual:  ${actualMiles} miles (${(actualMiles / 10).toFixed(2)}% of goal)`
  );
}

function milesFromTarget() {
  if (!actualMiles) {
    return;
  }

  const difference = (goalForToday() - actualMiles).toFixed(2);
  const daysDifference = (Math.abs(difference) / milesPerDay()).toFixed(2);
  const status = difference >= 0 ? "BEHIND" : "AHEAD of";

  console.log(
    `\n🏃‍♂️ ${Math.abs(difference)} miles (${daysDifference} days) ${status} pace`
  );
}

function estimatedEndDate() {
  if (!actualMiles) {
    return;
  }

  const percentOfGoal = goalForToday() / actualMiles;
  const finishDayOfYear = (percentOfGoal * 366).toFixed();
  console.log(`🎯 Estimated finish date: ${dateFromDay(finishDayOfYear)}`);
}

console.log(
  `Goal:    ${goalForToday().toFixed(2)} miles (${(goalForToday() / 10).toFixed(
    2
  )}% of goal)`
);
compareActualMiles();
milesFromTarget();
estimatedEndDate();