JS Curried Function (Converter 2)

curried-function-2-converter.js

const converterOld2 = (toUnit) => (factor) => (offset) => (input) => {
  const converterOffset = offset || 0;
  return [((converterOffset + input) * factor).toFixed(2), toUnit].join(' ');
};

const kmConverterWithUnit = converterOld2('km'); // function with a single params
const kmConverterWithFactor = kmConverterWithUnit(1.60936); // function with a single params
const kmConverter = kmConverterWithFactor(undefined); // function with a single params
console.log('kmConverter : ', kmConverter);
console.log('kmConverter(10) : ', kmConverter(10)); //  "16.09 km"

const convert10MilesToKm11 = converterOld2('km')(1.60936)(undefined)(10);
const convert20MilesToKm12 = converterOld2('km')(1.60936)(undefined)(20);
const convert30MilesToKm13 = converterOld2('km')(1.60936)(undefined)(30);

console.log('convert10MilesToKm11 : ', convert10MilesToKm11); //  "16.09 km"
console.log('convert20MilesToKm12 : ', convert20MilesToKm12); //  "32.19 km"
console.log('convert30MilesToKm13 : ', convert30MilesToKm13); //  "48.28 km"