Weird to see functional programming after so much OO

sanitizer.js

const maxLength = (firstString) => (secondString) => {
  return firstString.length > secondString.length ?
    firstString.length :
    secondString.length
}

module.exports = { maxLength }

sanitizer.tests.js

const sanitizer = require('../src/sanitizer')

describe('#maxLength', () => {
  test('should return 2 for "b" and "bc"', () => {
    let maxLengthBetweenBAnd = sanitizer.maxLength('b')
    expect(maxLengthBetweenBAnd('bc')).toEqual(2)
  })

  test('should return 2 for "b" and "bc"', () => {
    let maxLengthBetweenBcAnd = sanitizer.maxLength('bc')
    expect(maxLengthBetweenBcAnd('b')).toEqual(2)
  })

  test('should return 0 for "" and ""', () => {
    let maxLengthBetweenNullAnd = sanitizer.maxLength('')
    expect(maxLengthBetweenNullAnd('')).toEqual(0)
  })

  test('should return 5 for "abcde" and "abcde"', () => {
    let maxLengthBetweenAbcdAnd = sanitizer.maxLength('abcde')
    expect(maxLengthBetweenAbcdAnd('abcde')).toEqual(5)
  })
})