Days ago

Calculates the date of n days ago from today as a string representation.

• Use the Date constructor to get the current date.
• Use Math.abs() and Date.prototype.getDate() to update the date accordingly and set to the result using Date.prototype.setDate().
• Use Date.prototype.toISOString() to return a string in yyyy-mm-dd format.

const daysAgo = n => {
  let d = new Date();
  d.setDate(d.getDate() - Math.abs(n));
  return d.toISOString().split('T')[0];
};

daysAgo(20); // 2020-09-16 (if current date is 2020-10-06)