feat: i18n for nodejs

src/i18n/index.ts

@@ -1,4 +1,6 @@
 
+import isNodeJs from 'detect-node'
+
 import en from './en'
 import es from './es'
 
@@ -24,8 +26,17 @@ const locales = (<L extends { [n: string]: LOCALE } /** type checking */> (l: L)
 
 // detect browser language
 const lang = (() => {
+  let userLangs: readonly string[]
+  if (!isNodeJs) {
+    userLangs = navigator.languages
+  } else {
+    const env = process.env
+    const l = env.LC_ALL || env.LC_MESSAGES || env.LANG || env.LANGUAGE || ''
+    userLangs = [l.slice(0, 2)]
+  }
+
   const names = Object.keys(locales)
-  const _lang = navigator.languages.find(l => {
+  const _lang = userLangs.find(l => {
     // find the first occurrence of valid languages
     return names.includes(l)
   })