Growth

/** This can be replace with Intl.NumberFormatter */
commafy = (num) => {
  const [whole, decimal] = num.toString().split('.');
  const collection = [];
  const places = whole.split('');
  while (places.length > 0) {
    const three = [];
    for (let i = 0 ; i < 3 ; i++) {
      if (places.length) {
        three.unshift(places.pop());
      }
    }
    
    if (three.length > 0) {
      collection.unshift(three.join(''));
    }
  }

  let formattedNumber = collection.join(',');
  if (decimal) {
    formattedNumber += `.${decimal}`;
  }

  return formattedNumber;
}

/** commafy can be replaced by Intl.NumberFormatter! */

growth = (factor = 1.01, weeks = 52, infected = 109_000, mortality = 0.035, population = 7_600_000_000) => {
  const now = new Date();
  const formatter = new Intl.NumberFormat();
  for (let i = 1 ; i <= weeks ; i++) {
    infected = Math.round(infected * factor);
    const deaths = Math.round(infected * mortality);
    const week = new Date(now.setDate(now.getDate() + 7));
    console.log("Week", (i).toString().padStart(3), week.toDateString(),
      "\t",
      "infected", formatter.format(infected).padStart(16),
      "\t\t", 
      "deaths", formatter.format(deaths).padStart(12));
    if (infected > population) break;
  }
}