Calculate the fiscal year and fiscal quarter easily in JavaScript. Definitions can be reduced to one liners.

fiscalQuarter.js

function fiscalQuarter(date, opt_monthStart /* default: 9 (October) */) {
  opt_monthStart = opt_monthStart == undefined ? 9 : opt_monthStart;
  var month = date.getMonth(),
      monthIndex = ((month - opt_monthStart) + 12) % 12;
  return ~~(monthIndex / 3) + 1;
}

fiscalYear.js

function fiscalYear(date, opt_monthStart /* default: 9 (October) */) {
  opt_monthStart = opt_monthStart == undefined ? 9 : opt_monthStart;
  var month = date.getMonth(),
      year = date.getFullYear(),
      yearOffset = Math.floor((month - ((opt_monthStart % 12) || 12)) / 12) + 1;
  return yearOffset + year;
}