All About "Time" in Java Script

 

While using date & time we always want to display time in local time, for example india is GMT + 5:30.

But what's GMT and UTC ?

For programmers building business-oriented apps, the upshot is that UTC is the new GMT. You can use the terms interchangeably, with the difference being literally less than a second. So for all practical purposes in most apps, no difference at all.

ref : https://stackoverflow.com/questions/48942916/what-is-the-difference-between-utc-and-gmt

How do we store time ?

In computer we store time at 32-bit interger which is linux UTC epoch time. 

Try this code :

From where Time zone is decided ?

Time zone comes seperately from local setting either from your computer setting or mobile setting.

So based on you want to display local time ? or UTC time ? javascript convert epoch time into suitable string.

Firebase timestamp vs Javascript Date :

https://stackoverflow.com/questions/52247445/how-do-i-convert-a-firestore-date-timestamp-to-a-js-date

https://firebase.google.com/docs/projects/locations

https://firebase.google.com/docs/reference/android/com/google/firebase/Timestamp