Javascript下判断是否为闰年的Datetime包

/** 
* jscript.datetime package 
* This package contains utility functions for working with dates and times. 
*/ 
/*命名空间*/ 
if (typeof jscript == 'undefined') { 
jscript = function() { } 
} 

jscript.datetime = function() { } 

/** 
* This function will return the number of days in a given month and year, 
* taking leap years into account.（这个函数返回所给某年、某月的天数，并且考虑了闰年的情况） 
* 
* @param inMonth The month, where January = 1 and December = 12. 
* @param inYear The year to check the month in. 
* @return The number of days in the specified month and year. 
*/ 
jscript.datetime.getNumberDaysInMonth = function(inMonth, inYear) { 

inMonth = inMonth - 1; 
var leap_year = this.isLeapYear(inYear); 
if (leap_year) { 
leap_year = 1; 
} else { 
leap_year = 0; 
} 
/*4, 6, 9, 11 月为 30 天，注意上面的 inMonth = inMonth - 1*/ 
if (inMonth == 3 || inMonth == 5 || inMonth == 8 || inMonth == 10) { 
return 30; 
} else if (inMonth == 1) {/*2 月为 28 或者 29 天，视是否为闰年而定*/ 
return 28 + leap_year; 
} else {/*其它月则为 31 天*/ 
return 31; 
} 

} // End getNumberDaysInMonth(). 


/** 
* This function will determine if a given year is a leap year. 
*（这个函数用来确定是否为闰年） 
* @param inYear The year to check. 
* @return True if inYear is a leap year, false if not. 
*/ 
jscript.datetime.isLeapYear = function(inYear) { 

if ((inYear % 4 == 0 && !(inYear % 100 == 0)) || inYear % 400 == 0) { 
return true; 
} else { 
return false; 
} 

} // End isLeapYear().