Banx Walk Safe: same sidewalk, two heat loads

This is a submission for the DEV Weekend Challenge: Dog Days Edition.

What I Built

Same sidewalk. Two bodies. Two completely different heat loads.

Banx is my French Bulldog. Born October 5, 2022. He weighs 35 pounds - seven above the 28-pound ceiling in the French Bull Dog Club of America conformation standard. I call him my XL. He is purebred and he has never had airway surgery. The face that makes him Banx is also the conformation that puts French Bulldogs at higher risk of obstructed breathing and heat-related illness.

Dogs cool themselves mostly by panting. Flat-faced dogs can do it less efficiently, and how much varies a lot between individual dogs. So the same afternoon - same sun, same pavement, same humidity - is a walk for one dog and something else entirely for him. Nothing on the outside tells you that.

Enter a location. It pulls temperature and humidity, computes a heat index, and shows the load on a flat-faced dog beside a longer-muzzle dog across the day. Then it helps me think through the question I actually have when he's standing at the door: how stressful do the conditions look right now, how does that change with activity, and when does the environment get more favorable? It does not medically answer that for him, and the section below says exactly why it can't.

• Demo Live: https://banx-walk-safe.vercel.app
• Geolocation or city search. Works if you deny location. No API key.
• Code: Vanilla HTML / CSS / JS. No framework. Repo is the project folder on the machine that built it; the production artifact is the Vercel deploy above.
• Weather: Open-Meteo.
• Heat index: NOAA/NWS Rothfusz / Steadman family.

Why I Built It

When I first got him I didn't know how any of this worked. We started at Ledge Street Park in Nashua and took the trails toward Main Street. First ten minutes he's got everything - all over the place, into everything, full Banx. Then he changes. He stops being all over it and starts just observing