Middleware

Source
This example shows how to add route middleware with the middleware/ directory or with a plugin, and how to use them globally or per page.
redirect-me.ts
Open docs
export default defineNuxtRouteMiddleware((to) => {
  const { $config } = useNuxtApp()
  if ($config) {
    console.log('Accessed runtime config within middleware.')
  }
  console.log('Heading to', to.path, 'but I think we should go somewhere else...')
  return '/secret'
})
https://middleware.example.nuxt.space
Read more in Docs > Guide > Directory Structure > Middleware.