Question: Is there anyway to set the global/default timezone in JS on the browsers side?

E.g. if I have some date that are `+1300` and the user is `-0800` it converts the times. But I always want to show the times as `+1300`.

My application is already very large so I'm hoping I can just set it in one place, otherwise it will involve going though hundreds of lines of code to adjust anywhere a date is used.

Answer: 
No. There is only one global timezone: UTC - unfortunately it's not the default in JS, you have to use the [`…UTC…` methods](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date) explicitly to get away from the user's local timezone.

You cannot set a timezone in JavaScript. Start with UTC and add/subtract hours if you want to display a custom timezone, like in [this example](https://stackoverflow.com/a/14992195/1048572).

> 
> it will involve going though hundreds of lines of code to adjust anywhere a date is used.
> 
> 
> 

No. You only need to adjust the lines where a datetime is read or written. If the user does input dates according to his local timezone, you don't even need to fix that - only where you want to output it.
JavaScript has a built in method to retrieve the timezone offset of the current machine:

```
var d = new Data();
var offset = d.getTimezoneOffset();

```

In the above example, offset would be the minutes offset from UTC to Local Time. If you know your own offset, you can write a global method to take theirs and run a conversion.