modulate.js

export default function modulate(
  input,
  [inputRangeInitial, inputRangeFinal],
  [outputRangeInitial, outputRangeFinal],
  limit
) {
  const constrain = (result, low, high) =>
    Math.max(Math.min(result, high), low);
  const result =
    ((input - inputRangeInitial) / (inputRangeFinal - inputRangeInitial)) *
      (outputRangeFinal - outputRangeInitial) +
    outputRangeInitial;

  if (!limit) return result;

  return outputRangeInitial < outputRangeFinal
    ? constrain(result, outputRangeInitial, outputRangeFinal)
    : constrain(result, outputRangeFinal, outputRangeInitial);
}