Tuesday, July 26, 2011

Calculating working days between two dates with Javascript

Here’s a script that will calculate the number of working days between two Date objects in Javascript.  I had a hard time finding an accurate one online so I wrote one myself – please use with caution as it has not been rigorously tested.

Note that the calculation considers the difference between today and today to equal 1.  I’m using this to present the number of days left before an event, and in my case on the day of the event it makes sense to see “1 day” instead of “0 days.”  

function workingDaysBetweenDates(startDate, endDate) {

// Validate input
if (endDate < startDate)
return 0;

// Calculate days between dates
var millisecondsPerDay = 86400 * 1000; // Day in milliseconds
startDate.setHours(0,0,0,1); // Start just after midnight
endDate.setHours(23,59,59,999); // End just before midnight
var diff = endDate - startDate; // Milliseconds between datetime objects
var days = Math.ceil(diff / millisecondsPerDay);

// Subtract two weekend days for every week in between
var weeks = Math.floor(days / 7);
var days = days - (weeks * 2);

// Handle special cases
var startDay = startDate.getDay();
var endDay = endDate.getDay();

// Remove weekend not previously removed.
if (startDay - endDay > 1)
days = days - 2;

// Remove start day if span starts on Sunday but ends before Saturday
if (startDay == 0 && endDay != 6)
days = days - 1

// Remove end day if span ends on Saturday but starts after Sunday
if (endDay == 6 && startDay != 0)
days = days - 1

return days;
}

4 comments:

Craig Hamer said...

Hi ken,

Just wanted to drop a note to say this is the most concise and straight forward example I've seen. I's also the most accurate, so many thanks!!

Craig

Craig Hamer said...

Hi ken,

Just wanted to drop a note to say this is the most concise and straight forward example I've seen. I's also the most accurate, so many thanks!!

Craig

wabush said...

Several examples on stack overflowdid not work - this one did, thanks!

Dan Hutson said...

Thanks. This is exactly what I was looking for.