Coffeescript to find difference in date

datediff

#!/usr/local/bin/coffee

SEC = 1000
MIN = SEC * 60
HOUR = MIN * 60
DAY = HOUR * 24
WEEK = DAY * 7

if process.argv.length != 4
	console.log "Insufficient arguments to complete call"
	process.exit 1

start = new Date(process.argv[2]).getTime()
end = new Date(process.argv[3]).getTime()

if isNaN(start)
	console.log "invalid date: "+ process.argv[2]
	process.exit 2

if isNaN(end)
	console.log "invalid date: "+ process.argv[3]
	process.exit 2

diff = end - start
unit = "millis"
if diff >= WEEK
	diff /= WEEK
	unit = "weeks"
else if diff >= DAY
	diff /= DAY
	unit = "days"
else if diff >= HOUR
	diff /= HOUR
	unit = "hours"
else if diff >= MIN
	diff /= MIN
	unit = "minutes"
else if diff >= SEC
	diff /= SEC
	unit = "seconds"

console.log(diff + " " + unit)