Here you can find the source of isLeapYear()
Date.prototype.isLeapYear = function () { var year = this.getFullYear(); return ((year & 3) == 0 && (year % 100 || (year % 400 == 0 && year))); }
Date.prototype.isLeapYear = function() { var year = this.getFullYear(); if ((year & 3) != 0) return false; return ((year % 100) != 0 || (year % 400) == 0); };
Date.prototype.isLeapYear = function () { return this.getFullYear()%4?0:this.getFullYear()%100?1:this.getFullYear%400?0:1
Date.prototype.isLeapYear = function() { var year = this.getFullYear(); if((year & 3) != 0) return false; return ((year % 100) != 0 || (year % 400) == 0); }; Date.prototype.getDOY = function() { var dayCount = [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334]; var mn = this.getMonth(); var dn = this.getDate(); ...
Date.isLeapYear = function(year) { return (((year % 4 === 0) && (year % 100 !== 0)) || (year % 400 === 0)); }; Date.getDaysInMonth = function(year, month) { return [31, (Date.isLeapYear(year) ? 29 : 28), 31, 30, 31, 30, 31, 31, 30, 31, 30, 31][month]; }; Date.prototype.isLeapYear = function() { return Date.isLeapYear(this.getFullYear()); }; ...
Date.prototype.isLeapYear = function(){ return (0==this.getYear()%4 && ((this.getYear()%100 != 0) || (this.getYear()%400 == 0)));
Date.prototype.isLeapYear = function () { return new Date(this.getFullYear(), 1, 29).getDate() == 29; };
Date.prototype.isLeapYear = function() { return Date.isLeapYear(this.getFullYear()); };
Date.prototype.isLeapYear = function () var y = this.getFullYear(); return (((y % 4 === 0) && (y % 100 !== 0)) || (y % 400 === 0)); };
Date.isLeapYear = function(year) { return (((year % 4 === 0) && (year % 100 !== 0)) || (year % 400 === 0)); };