The stringdate.js provides functions handling String as a Date.

Valid format is "yyyy-MM-dd" in general. "yyyy-MM" is allowed for getLastDate() and isLeapYear(). "yyyy" is allowed for isLeapYear() only.

Note that the string should be valid syntactically and semantically. It means "2015-04-31" is not valid in stringdate.js while it makes a date of May 1st, 2015 in vanilla JavaScript.

All functions in below should applied on valid format, otherwise it throws Error.

String.prototype.getYear() : Returns year of 4-digits.

String.prototype.getMonth() : Returns month between 1 and 12. : Note that vanilla JavaScript Date object's getMonth() returns integer between 0 and 11.

String.prototype.getDate() : Returns date of month between 1 and 31.

// get year"2015-03-14".getYear();// 2015// get month"2015-03-14".getMonth();// 3// get date of month"2015-03-14".getYear();// 14// get day of week"2015-03-14".getDay();// 6

String.prototype.getLastDate() : Returns last date of the month. Date format can be either "yyyy-MM-dd" or "yyyy-MM".

String.prototype.isLeapYear() : Determine whether the year is leap year or not. Date format can be one of "yyyy-MM-dd", "yyyy-MM", or "yyyy".

// get last date"2015-02-01".getLastDate();// 28"2015-02".getLastDate();// 28// determine leap year// 2015"2015-02-01".isLeapYear();// false"2015-02".isLeapYear();// false"2015".isLeapYear();// false// 2016"2016-02-01".isLeapYear();// true"2016-02".isLeapYear();// true"2016".isLeapYear();// true

String.prototype.getDaysFrom(target) : Returns days between this date and target date. It returns positive when target is past, or negative when target is future. You can use this function as subtraction operator -.

String.prototype.addDays(days) : Returns new date after/before the date. It returns future date for positive days, or past date for negative days. You can use this function as addition operator +.

// get days between two dates"2015-03-31".getDaysFrom("2015-03-01");// 30"2015-04-01".getDaysFrom("2015-06-30");// -90// get date after/before a date"2015-03-14".addDays(100);// "2015-06-22""2015-03-14".addDays(-28);// "2015-02-14"

varcount=0;for(vardate="2015-04-01";date<="2015-06-30";date=date.addDays(1))if(date.getDay()!=0&&date.getDay()!=6)count++;console.log(count);// 65

MIT License