vue-i18n route for multi language

i want to use vue-i18n with /:lang in routes ... but i want ignore default lang, for example : www.domain.com/somwhere use my default lang and www.domain.com/fr/somwhere use french version .... is any way to do this ?

now it is like this:

www.domain.com/en default
www.domain.com/fr french
www.domain.com/du dutch

it has to be like this :

www.domain.com/ default
www.domain.com/fr french
www.domain.com/du dutch

my route.js file is like :

 {
    path: "/",
    redirect: `/${i18n.locale}`
  },
  {
    path: "/:lang",
    async beforeEnter(to, from, next) {
      console.log(i18n.locale);
      if (!i18n.availableLocales.includes(to.params.lang)) {
        window.location.replace(`${i18n.fallbackLocale}${to.path}`);
      } else {
        next();
      }
    },
    component: {
      render(c) {
        return c("router-view");
      }
    },
    children: [
      {
        path: "/",
        name: "LandingPage",
        component: () =>
          import(
            /* webpackChunkName: "LandingPage" */ "@/views/LandingPage/index"
          )
      },
}