get-change-value.ts

interface GetChangeValue {
  value: number;
  containerWidth?: number;
  min: number;
  max: number;
  step: number;
  precision?: number;
}

export function getChangeValue({
  value,
  containerWidth,
  min,
  max,
  step,
  precision,
}: GetChangeValue) {
  const left = !containerWidth
    ? value
    : Math.min(Math.max(value, 0), containerWidth) / containerWidth;
  const dx = left * (max - min);
  const nextValue = (dx !== 0 ? Math.round(dx / step) * step : 0) + min;
  const nextValueWithinStep = Math.max(nextValue - (nextValue % step), min);

  if (precision !== undefined) {
    return Number(nextValueWithinStep.toFixed(precision));
  }

  return nextValueWithinStep;
}