Different behaviour for different firebase functions

index.js

const functions = require("firebase-functions");
const express = require("express");

let staticValue = { message: 'Hello World!' }

// you don't want this then as it will be a single instance of helloWorld_app. You don't really have control when the instance is up or down unless 
// you configure that in the function with "minInstances" etc
const app = express();

app.get('/short', (req, res) => {
    setTimeout(() => {
        staticValue.message = 'Hello short!';
        res.send(staticValue.message);
    }, 2000);
});

app.get('/long', (req, res) => {
    setTimeout(() => {
        res.send(staticValue.message);
    }, 5000);
});

exports.helloWorld_app = functions.https.onRequest(app);

// you want these and then map a nice route in hosting if you want it
// we are actually running in different vm's so this is fine
exports.helloWorld_short = functions.https.onRequest((req, res) => {
    setTimeout(() => {
        staticValue.message = 'Hello short!';
        res.send(staticValue.message);
    }, 2000);
});

// yeah we are lol
exports.helloWorld_long = functions.https.onRequest((req, res) => {
    setTimeout(() => {
        res.send(staticValue.message);
    }, 5000);
});

// each request here will be a new instance of helloWorld_random so it will only have it's own context too
exports.helloWorld_random = functions.https.onRequest((req, res) => {
    const random = Math.round(Math.random() * 10000);
    functions.logger.log(`waiting milliseconds: ${random}`);

    setTimeout(() => {
        staticValue.message = `Hello random ${random}`;
        res.send(staticValue.message);
    }, random);
});