Modulate function - good for parallax on scroll or movement on scroll

modulate.js

export function modulate(value, rangeA, rangeB, limit) {
  let fromHigh, fromLow, result, toHigh, toLow
  if (limit == null) {
    limit = false
  }
  fromLow = rangeA[0]
  fromHigh = rangeA[1]
  toLow = rangeB[0]
  toHigh = rangeB[1]
  result = toLow + ((value - fromLow) / (fromHigh - fromLow)) * (toHigh - toLow)
  if (limit === true) {
    if (toLow < toHigh) {
      if (result < toLow) {
        return toLow
      }
      if (result > toHigh) {
        return toHigh
      }
    } else {
      if (result > toLow) {
        return toLow
      }
      if (result < toHigh) {
        return toHigh
      }
    }
  }
  return result
}