Date difference in Javascript (ignoring time of day)

Question

I\'m writing an equipment rental application where clients are charged a fee for renting equipment based on the duration (in days) of the rental. So, basically, (daily fee *

Answer 1

I would also suggest having a look at the incredible moment.js library. It has a versatile diff function, which you can use to solve the above example as follows:

function is_same_date(startDate, endDate) {
   var startMoment = moment(startDate).clone().startOf('day'),
       endMoment = moment(endDate).clone().startOf('day');
   return startMoment.diff(endMoment, 'days') == 0;
}

Here are some examples using moment.js diff:

> d1 = new Date(2012,04,04,0,0)
Fri May 04 2012 00:00:00 GMT-0400 (EDT)

> d2 = new Date(2012,04,03,23,0)
Thu May 03 2012 23:00:00 GMT-0400 (EDT)

> d3 = new Date(2012,04,05,23,0)
Sat May 05 2012 23:00:00 GMT-0400 (EDT)

> moment(d2).diff(d1, 'days')
0

> moment(d1).diff(d2, 'days')
0

> moment(d1).diff(d3, 'days') // uh oh. this is why we use `startOf`
-2

> moment(d2).diff(d3, 'days')
-2

> moment(d3).startOf('day') // this modified d3, sets the time to 00:00:00.0000
> d3
Sat May 05 2012 00:00:00 GMT-0400 (EDT)

If timezones are a concern, you can also use moment.utc() to convert to a normalized timezone.