Calculates sales tax

salesTax.js

const calculateSalesTax = function(salesData, taxRates) {
  let result = {};
  for (let i = 0; i < salesData.length; i++) {
    if (result[salesData[i]["name"]] === undefined) {
      const totalSales = salesData[i]["sales"].reduce((accumulator, currentValue) => accumulator + currentValue);
      result[salesData[i]["name"]] = {
        totalSales,
        totalTax: totalSales * taxRates[salesData[i]["province"]],
      };
    } else {
      let totalSalesOfThisProvince = salesData[i]["sales"].reduce((accumulator, currentValue) => accumulator + currentValue);
      result[salesData[i]["name"]]["totalSales"] += totalSalesOfThisProvince;
      result[salesData[i]["name"]]["totalTax"] += totalSalesOfThisProvince * taxRates[salesData[i]["province"]];
    }
  }
  return result;
};

const salesTaxRates = {
  AB: 0.05,
  BC: 0.12,
  SK: 0.10
};

const companySalesData = [
  {
    name: "Telus",
    province: "BC",
    sales: [ 100, 200, 400 ]
  },
  {
    name: "Bombardier",
    province: "AB",
    sales: [ 80, 20, 10, 100, 90, 500 ]
  },
  {
    name: "Telus",
    province: "SK",
    sales: [ 500, 100 ]
  }
];

console.log(calculateSalesTax(companySalesData, salesTaxRates));