Express routes and middleware with Firebase Cloud Functions - express

Question

Question
How do I use Express within Firebase Cloud Functions?
Expectations
Using either of the URLs I've setup, I expect to see, "Hello from Express on Firebase!" in the console logs.
Why? My understanding is, "*" means all routes requested should response.send("Hello from Express on Firebase!");
app.get("*", (_request, response) => {
response.send("Hello from Express on Firebase!");
});
Issue
When I use, https://us-central1-myapp.cloudfunctions.net/helloWorld I get the expected Hello from Firebase! in the logs. Should I also see "Hello from Express on Firebase!"?
When I use, https://us-central1-myapp.cloudfunctions.net/api, I get a 404 error
The URL, https://us-central1-myapp.cloudfunctions.net/api is the issue. See why in the answer below.
Code
// Express
import express = require("express");
const app = express();
const cors = require("cors")({
origin: "*"
});
app.use("*", cors);
// Firebase Functions SDK
import functions = require("firebase-functions");
app.get("*", (_request, response) => {
response.send("Hello from Express on Firebase!");
});
exports.api = functions.https.onRequest(app);
exports.helloWorld = functions.https.onRequest((_request, response) => {
response.send("Hello from Firebase!");
});
tl;dr
An example of what I'm hoping to accomplish is here, but none of the code examples worked for me. I get I get a 404 error with each one.
The Express Documentation here shows a similar HelloWorld example, but I confuse how Firebase takes the place of app.listen(3000, () => console.log('Example app listening on port 3000!'))
Is cors working properly in my example code? Although I get the expected response and log, Chrome console warns: Cross-Origin Read Blocking (CORB) blocked cross-origin response https://appengine.google.com/_ah/lo....
I have a Slack App that is hitting these URLs (I hit them with chrome too). Eventually, I'd like to use Botkit middleware in my Google Cloud Functions. I don't yet grasp proper setup of Express app.use() and app.get()

Answer 1

Answer
I made a simple mistake by treating /api as a function when it's actually a part of the path.
By using this URL with the trailing /
https://us-central1-myapp.cloudfunctions.net/api/
I'm now hitting the Express route and function.