has-unicode

Try to guess if your terminal supports unicode

 var hasUnicode = require("has-unicode")

if (hasUnicode()) {
  // the terminal probably has unicode support
}

 var hasUnicode = require("has-unicode").tryHarder
hasUnicode(function(unicodeSupported) {
  if (unicodeSupported) {
    // the terminal probably has unicode support
  }
})

Detecting Unicode

What we actually detect is UTF-8 support, as that's what Node itself supports.
If you have a UTF-16 locale then you won't be detected as unicode capable.

Windows

Since at least Windows 7, cmd and powershell have been unicode capable,
but unfortunately even then it's not guaranteed. In many localizations it
still uses legacy code pages and there's no facility short of running
programs or linking C++ that will let us detect this. As such, we
report any Windows installation as NOT unicode capable, and recommend
that you encourage your users to override this via config.

Unix Like Operating Systems

We look at the environment variables LC_ALL, LC_CTYPE, and LANG in
that order. For LC_ALL and LANG, it looks for .UTF-8 in the value.
For LC_CTYPE it looks to see if the value is UTF-8. This is sufficient
for most POSIX systems. While locale data can be put in /etc/locale.conf
as well, AFAIK it's always copied into the environment.