Quarter of year

Returns the quarter and year to which the supplied date belongs to.

• Use Date.prototype.getMonth() to get the current month in the range (0, 11), add 1 to map it to the range (1, 12).
• Use Math.ceil() and divide the month by 3 to get the current quarter.
• Use Date.prototype.getFullYear() to get the year from the given date.
• Omit the argument, date, to use the current date by default.

const quarterOfYear = (date = new Date()) => [
  Math.ceil((date.getMonth() + 1) / 3),
  date.getFullYear()
];

quarterOfYear(new Date('07/10/2018')); // [ 3, 2018 ]
quarterOfYear(); // [ 4, 2020 ]