Which JavaScript function? The two main ones return two differing results for my browser.

  Intl.DateTimeFormat().resolvedOptions().timeZone

  > "Australia/Melbourne"

Which is UTC +11.

   new Date().getTimezoneOffset()

   > -710

Which is roughly UTC +11.8.

If you're going to shoebox me into a particular timezone - tell me what it is, and let me change it.