Date.prototype.end = function () { if (this._is) { this._is = false; return this.clone().addDays(1).getDate() == 1; } this.setDate(1); return this.addMonths(1).addDays(-1); }

Date.prototype.start = function () { if (this._is) { this._is = false; return this.getDate() == 1; } this.setDate(1); return this; }

/*
Example Usage:
new Date(2012,2-1,1).end().getDate() === 29
new Date(2012,2-1,1).next().month().end().getDate() === 31
Date.november().end().getDate() === 30
new Date(2011,2,15).is().end() === false
// The following are true for *any* Date:
new Date().end().is().end() === true
new Date().start().getDate() === 1
new Date().start().is().start() === true
new Date().end().is().start() === false
new Date().start().is().end() === false
*/

In the current version of datajs there appears to be a function called weekday:

Date.prototype.weekday = function () {
if (this._is) {
this._is = false;
return !this.is().sat() && !this.is().sun();
}
return false;
}

However, this returns ‘false’ if you do
Date().parse(“8:30am”).next().weekend();
instead of showing the next weekday.

The datajs code could be extended to include a ‘workday’ and ‘weekend’ function which allow next().workday() and prev().weekend(), assuming Mon-Fri are work days and Saturday is the start of the weekend.

Date.prototype.weekend = function() {
if (this._is) {
this._is = false;
return this.is().saturday() || this.is().sunday();
}
return this.saturday();
}

/**
Next Workday is the next day, skipping weekends (Saturdays and Sundays).

Example Usage and Output:

var now, nextWorkday, prevWorkday;

now = new Date(“8:30 am July 17, 2010″)
// Sat Jul 17 2010 08:30:00
now.is().workday();
// false … Satuday is the weekend, not a workday

// skip weekends and go straight to Monday.
nextWorkday = now.clone().next().workday()
// Mon Jul 19 2010 08:30:00
nextWorkday.is().workday();
// true … Monday is a weekday.

// Previous workday from a Monday, Saturday or Sunday is a Friday, not a Monday.
prevWorkday = nextWorkday.clone().prev().workday()
// Fri Jul 16 2010 08:30:00
prevWorkday.is().workday()
// true … Friday is a weekday

now.clone().next().day().is().workday();
// false … Saturday and Sunday are not work days.

*/
Date.prototype.workday = function () {
if (this._is) {
this._is = false;
return !this.is().weekend();
}
this.day();
if (this.is().weekend()) {
this._orient < 0 ? this.friday() : this.monday();
}
return this;
}

/*
Licensed under The MIT License
… feel free to include this code in next release of datajs
*/

cheers,
and keep up the good work!

It looks like the contact form on your contact page is broken, so I’m posting here instead in the hope that you will see this comment.

Are you still maintaining / doing any sort of active development on this code? I’m asking because it’s really quite awesome and I’d like to use it in a Thunderbird add-in I maintain, but there’s one little feature missing… I’d like to be able to say, for example, “8:30 am next weekday” and have “weekday” mean the next day if it is currently Monday through Thursday, or the following Monday if it is currently Saturday or Sunday.

I looked briefly at the code to see if this would be something easy to add, and boy, it’s complicated!

@Mike, because its not only used for days. You can also use d1.same().month(d2) or d1.same.hour(d2) for example, to check whether two event are in the same month (of the same year) or the same hour (of the same day of the same month of the same year) respectively.