Javascript function to add or decrease days to a date.

addOrDecreaseDaysToDate.ts

/**
* Function to add or decrease days to a date
* @param {string} date - With the date (With at least yyyy-mm-dd date format)
* @param {number} days - With the days
* @param {boolean} action - True to increase days or false to decrease days
* @returns {string} With the the new date
*/
export const addOrDecreaseDaysToDate = (date: string, days: number, action: boolean): string => {
 const result = new Date(date);
  action ? result.setDate(result.getDate() + days) : result.setDate(result.getDate() - days);
  return result.toISOString();
};