How can I configure the local IP for my server? - node.js

Question

I'm just getting used to NodeJS and MongoDB so please go gentle! I'm trying to "console.log" the "network Interfaces" to find the IP address.
No matter what I do, I keep getting an error:
"TypeError: Cannot read property '1' of undefined "
I suspect that it's this code in line 11:
const ip = networkInterfaces.Ethernet[1].address;
Here is what is in my app.js file:
const express = require("express");
const app = express();
const mongoose = require("mongoose");
const morgan = require("morgan");
const bodyParser = require("body-parser");
const path = require("path");
const cors = require("cors");
const os = require("os");
const networkInterfaces = os.networkInterfaces();
const ip = networkInterfaces.Ethernet[1].address;
require("dotenv/config");
//import routes
const productRoute = require("./routes/product");
const cartRoute = require("./routes/cart");
const orderRoute = require("./routes/order");
const favoriteRoute = require("./routes/favorite");
const authRoute = require("./routes/auth");
const notification = require("./middlewares/pushNotification");
//Connect to DB
const dbURI = process.env.DB_CONNECTION;
mongoose.connect(
dbURI,
{
useNewUrlParser: true,
useUnifiedTopology: true,
useFindAndModify: false,
useCreateIndex: true,
},
() => {
app.listen(process.env.PORT, ip);
let dirPath = path.join(
__dirname,
"public/api/static/images/productPictures"
);
let dirPathUser = path.join(
__dirname,
"public/api/static/images/userprofile"
);
createDir(dirPath);
createDir(dirPathUser);
console.log("Connected to DB");
}
);
function createDir(dirPath) {
if (!fs.existsSync(dirPath)) {
fs.mkdirSync(dirPath, { recursive: true }, (err) => {
if (err) {
console.error("createDir Error:", err);
} else {
console.log("Directory is made!");
}
});
}
}
...

Answer 1

this answer will help you with
network interfaces
If you are trying to get the client IP then you can use
const RequestIp = require("#supercharge/request-ip");
const ip = RequestIp.getClientIp(req);
inside your API
or to get the current machine address you can use child process

Answer 2

I solved the issue by removing Ethernet[1].address with en0[1].
line 11 now reads:
const ip = networkInterfaces.en0[1].address;
I added this to the end of my App.js files:
const port = process.env.PORT || '3000';
const address = process.env.ADDRESS || '127.0.0.1';
app.listen(port,address, () => console.log('Server running on http:// ' + address + ':' + port +'/'));