refactorme.js

var customer = {
  "name": "martin",
  "rentals": [{
    "movieID": "F001",
    "days": 3
  }, {
    "movieID": "F002",
    "days": 1
  }]
};

var movies = {
  "F001": {
    "title": "Ran",
    "code": "regular"
  },
  "F002": {
    "title": "Trois Couleurs: Bleu",
    "code": "regular"
  }
};

function statement(customer, movies) {
  let totalAmount = 0;
  let frequentRenterPoints = 0;
  let result = `Rental Record for ${customer.name}\n`;
  for (let r of customer.rentals) {
    debugger;
    let movie = movies[r.movieID];
    let thisAmount = 0;

    // determine amount for each movie
    switch (movie.code) {
      case "regular":
        thisAmount = 2;
        if (r.days > 2) {
          thisAmount += (r.days - 2) * 1.5;
        }
        break;
      case "new":
        thisAmount = r.days * 3;
        break;
      case "childrens":
        thisAmount = 1.5;
        if (r.days > 3) {
          thisAmount += (r.days - 3) * 1.5;
        }
        break;
    }

    //add frequent renter points
    frequentRenterPoints++;
    // add bonus for a two day new release rental
    if (movie.code === "new" && r.days > 2) frequentRenterPoints++;

    //print figures for this rental
    result += `\t${movie.title}\t${thisAmount}\n`;
    totalAmount += thisAmount;
  }
  // add footer lines
  result += `Amount owed is ${totalAmount}\n`;
  result += `You earned ${frequentRenterPoints} frequent renter points\n`;

  return result;
}

var result = statement(customer, movies);
console.log(result);