nearest-periodic-value/src/nearest-periodic-value.js

Find the nearest value of a discrete periodic function, given a point.

/*jshint -W018 */

function nearestPeriodicValue(point, value, period) {

  var relation = (value - point) / period;

  // We're equidistant from the nearest point if the
  // distance from the point is a half-integer value
  // of our period.
  var equidistant = !(relation % 0.5) && relation % 1;

  // If we're equidistant, then we add a period to
  // ensure that we always pick the value in front
  var mod = equidistant ? period : 0;

  // Adjust our value by an amount given by the closest #
  // of periods contained in the distance between the point
  // and the value
  return mod + (value - period * Math.round(relation));
}

export default nearestPeriodicValue;