JavaScript Timestamp question

Question

What does these two lines do?

Math.floor(1293859512411 / 86400000)
Math.ceil((new Date().getTime()) / 86400000)

I understand it is something to do with time since epoch, but please explain the two lines.

Jon Skeet · Accepted Answer · 2011-08-28 15:05:29Z

3

Well, 86400000 is the number of milliseconds in a day - so

Math.ceil((new Date().getTime()) / 86400000)

is meant to be "the number of days elapsed since the Unix epoch at January 1st 1970 midnight UTC, rounding up".

The first line just returns the number of days between the Unix epoch and January 5th 2011.

edited Aug 28, 2011 at 15:05

answered Aug 5, 2011 at 5:30

Jon Skeet

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2 Comments

HoLyVieR Over a year ago

All number in javascript are 64 bits float. Even if the number is represented with an integer looking form it's actually a float. The .0 isn't needed.

Jon Skeet Over a year ago

@HoLyVieR: Thanks - will just remove the last part.

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