Method Date.isLeapYear

Check whether a date belongs to a leap year.

• Syntax Boolean Date.isLeapYear([ Boolean utc ])
  
  If utc is true then calculations are based on UTC time. If flase then the local time is used.
• Parameters

  Boolean utc (Optional)

  Set to true to use UTC; false to use local time

• Return value True if year of date is a leap year; otherwise false.
• Examples

  To check whether 1981 is a leap year (it is not)

  // Create a new date
  var d = new Date();
  // Set the year
  d.setFullYear(1981);
  // Output is false
  d.isLeapYear();

• Related Date.format   
• Resources There is a lengthy article on leap years at Wikipedia.org
• Download
  Download this function including dependencies
  Source

  Unless otherwise noted all code in the JSLab Standard Library is licensed as GPLv3. See http://www.gnu.org/licenses/gpl.html for the entire license.

  // ************************************************************************** // Copyright 2007 - 2009 Tavs Dokkedahl // Contact: http://www.jslab.dk/contact.php // // This file is part of the JSLab Standard Library (JSL) Program. // // JSL is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 3 of the License, or // any later version. // // JSL is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // You should have received a copy of the GNU General Public License // along with this program. If not, see <http://www.gnu.org/licenses/>. // *************************************************************************** // Retuns true if year is a leap year; otherwise false Date.prototype.isLeapYear = function(utc) { var y = utc ? this.getUTCFullYear() : this.getFullYear(); return !(y % 4) && (y % 100) || !(y % 400) ? true : false; };