liveh5-nuxt/app/plugins/i18n.js

import { Locale } from 'vant'
import enUS from 'vant/es/locale/lang/en-US'
import zhCN from 'vant/es/locale/lang/zh-CN'
import jaJP from 'vant/es/locale/lang/ja-JP'
import zhTW from 'vant/es/locale/lang/zh-TW'

export default defineNuxtPlugin(() => {

  Locale.use('zh-CN', zhCN)
  Locale.use('en-US', enUS)
  Locale.use('ja-JP', jaJP)
  Locale.use('zh-TW', zhTW)

  if (import.meta.client) {
    const i18n = useNuxtApp().$i18n
    const { setLocale } = i18n
    const lang = localStorage.getItem('lang')
    if (lang) {
      setLocale(lang)
      Locale.use(lang)
    }
    else {
      setLocale(i18n.locale.value)
      Locale.use(i18n.locale.value)
    }
  }
})