Function pctChange

packages/dataflows/src/returns.ts:68–73

(series: Series[], from: string, to: string)

}

function pctChange(series: Series[], from: string, to: string): number | null {
  const start = closeOn(series, from);
  const end = closeOn(series, to);
  if (start == null || end == null || start === 0) return null;
  return ((end - start) / start) * 100;
}

function addDays(date: string, days: number): string {
  const d = new Date(date + "T00:00:00Z");