Add fromUnixTime function

[envil]

I tried to find the function similar to moment.unix() where I want to create a date from an unix timestamp in date-fns but couldn't find it. Is it me couldn't find it or it's indeed not exist?

[leshakoss]

The best way to do it right now is to use getTime function which returns the milliseconds timestamp.

Math.floor(getTime(new Date()) / 1000)

[envil]

@leshakoss what I meant is to create a new Date object from the unix timestamp. I'm currently doing it like const date = new Date(epoch * 1000)

[leshakoss]

Oh, my bad. Every function in date-fns does accept a milliseconds timestamp instead of any date argument, so you can use them the same way that you're currently doing it: getISOWeeksInYear(epoch * 1000). Also parse from v1 and toDate from v2 could be used to convert ms timestamps to a date, and of course, using new Date constructor is a perfectly valid way to do it.

[envil]

Yep, my situation is I have to initiate the date from epoch time quite a lot in my application, so having the * 1000 magic number everywhere is quite irritating to me. I could write my own date util to create the date like fromUnix(epoch) that can return the date, but then what's the point to use a some library like date-fns. Also not many people know how to create the date from the epoch time, so this would be quite helpful I think.

[Kingwl]

👍 helpful to me,
i prefer to explicit convert rather than * 1000

[kossnocorp]

That's a good idea and easy to implement. My API suggestion is two functions: fromUnix() and toUnix().

I'm strictly against being "smart" and trying to guess if it's JS time or Unix time because that would cause unpleasant bugs. Also given that you receive the time in seconds, it's vital to know that JS has time in milliseconds because likely you will send the time back to the back-end.

Also, I recommend using ISO-8601 strings for cross-language communications because it does not only save you from this kind of problems but also preserves the original time zone.

[Kingwl]

I have already sent a pr for toUnix but named getUnixTime
#870

[kossnocorp]

@Kingwl oh wow, I did miss it 🤦‍♂️ Thank you a lot, I'll take a look.

[xkizer]

PR for this in #937

[kossnocorp]

fromUnixTime was released as date-fns@2.0.0-alpha.24: https://gist.github.com/kossnocorp/a307a464760b405bb78ef5020a4ab136#v200-alpha24