Responsive IP Address Tracker with Express, IPify, and Leaflet/Mapbox

Fun project -- you're able to search for both IPs and domains. Some questions:

1. Is there a more efficient way I could have identified whether input is an IP or domain?

2. I'm not the most experienced with Express -- is there another way I could simplify or improve the logic? (I decided to use an Express backend to help hide the API keys :), along with restricting how the Mapbox key can be used through their website).

Thanks for looking! Hope you like it!