Pure function carousel wrap

carousel.js

// Creates a helper function to create looping carousel slides.
// @param {number} arrIndex - Index of slide in array (starting from 0)
// @param {number} arrLength - The number of slides in the carousel
// @returns {function} offset - The helper function.

export const steps = (arrIndex, arrLength) => (progress) => {
  const wraps = ((arrIndex + 1) - progress) / arrLength
  const flooredWraps = Math.floor(wraps)

  return 0 - flooredWraps
}