`ExistentialAvailability` check if the response from passed URL returns `404` or not.
For example, `<ExistentialAvailability target="https://formulae.brew.sh/api/formula/git.json" />` will send a request to `target` and see if it returns with 404. For security reasons, `target` must send back `Access-Control-Allow-Origin: *` header for bridging across cross-site requests. If they don't support `Access-Control-Allow-Origin`, you might want to use `DedicatedAvailability` for dedicated response handling.
### DedicatedAvailability
`DedicatedAvailability` is for interacting with defined API endpoint to check availability.
For example, `<DedicatedAvailability service="<service>" />` will send a request to `https://namae.dev/availability/<service>/<query>` which is routed to `/api/services/<service>.js` in the repo.