parcel1.js

class Parcel {
  constructor(dimensions) {
    this.dimensions = dimensions;
    this.parcelSize = Parcel.returnParcelSize(dimensions);
    this.price = Parcel.calculatePrice(dimensions);
  }

  static get prices() {
    return {
      small: 3,
      medium: 5,
      large: 15,
      extraLarge: 30,
    };
  }

  static get parcelInfo() {
    return {
      small: { maxDimension: 10, price: 3 },
      medium: { maxDimension: 50, price: 8 },
      large: { maxDimension: 100, price: 15 },
      extraLarge: { maxDimension: null, price: 25 },
    };
  }

  static calculatePrice(dimensions) {
    // [1, 2, 3]
    // small / medium / large
    const parcelSize = Parcel.returnParcelSize(dimensions);
    const { price } = Parcel.parcelInfo[parcelSize];
    return price;
  }

  static isParcelRightSize(dimensions, maxDimension) {
    const biggestDimension = dimensions.slice().sort((a, b) => a < b)[0];
    return biggestDimension < maxDimension;
  }

  static returnParcelSize(dimensions) {
    let result;
    switch (true) {
      case Parcel.isParcelRightSize(
        dimensions,
        Parcel.parcelInfo.small.maxDimension
      ):
        result = 'small';
        break;
      case Parcel.isParcelRightSize(
        dimensions,
        Parcel.parcelInfo.medium.maxDimension
      ):
        result = 'medium';
        break;
      case Parcel.isParcelRightSize(
        dimensions,
        Parcel.parcelInfo.large.maxDimension
      ):
        result = 'large';
        break;
      default:
        result = 'extraLarge';
    }
    return result;
  }
}

// testing
const parcel = new Parcel([11, 2, 3]);
console.log(parcel.dimensions);
console.log(parcel.parcelSize);
console.log(parcel.price);

/////////////////////////////////////////////////////////////////

const { Parcel } = require('./test');

class Order {
  constructor(order, parcel, speedyStatus = false) {
    this.order = order;
    this.speedyStatus = speedyStatus;
    this.Parcel = parcel;
  }

  createOrder() {
    return this.order.map(parcel => new this.Parcel(parcel));
  }

  calculateTotal() {
    const arrayOfOrders = this.createOrder();
    const total = arrayOfOrders.reduce((sum, parcel) => {
      return sum + parcel.price;
    }, 0);
    return this.speedyStatus ? total * 2 : total;
  }

  returnResult() {
    return {
      order: this.createOrder(),
      totalCost: this.calculateTotal(),
    };
  }
}

const sampleOrder = [[1, 2, 3], [11, 2, 2], [51, 1, 1]];

const newOrder = new Order(sampleOrder, Parcel);
console.log('RESULT =>', newOrder.returnResult());