CORS error when serving angular with express - node.js

Question

I have 2 server.js files. One of them is inside the backend folder where when I run nodemon server.js on localhost:3000. And I'll start angular with ng serve inside the angular folder and login to my app no problem. Everything works. No CORS issue.
BUT
If I try to run my server.js file in the root directory where express serves my angular build folder. It starts up on localhost:8080, but when I try to login to my app, I get
inside my app.js file I have the following, which should be relevant. Another thing worth noting
is I made a docker version and that version gives me the CORS error too. So it seems to only work when running locally with ng serve and nodemon server.js
app.use((req, res, next) => {
res.header("Access-Control-Allow-Origin", "*");
res.header(
"Access-Control-Allow-Headers",
"Origin, X-Requested-With, Content-Type, Accept, Authorization"
);
res.header(
"Access-Control-Allow-Methods",
"GET, POST, PATCH, PUT, DELETE, OPTIONS"
);
next();
});
server.js file in backend folder (localhost:3000 No CORS error)
const app = require("./app");
const debug = require("debug")("node-angular");
const http = require("http");
const mongoose = require("mongoose");
var redis = require("redis");
var env = require("dotenv").config();
const normalizePort = val => {
var port = parseInt(val, 10);
if (isNaN(port)) {
e;
// named pipe
return val;
}
if (port >= 0) {
// port number
return port;
}
return false;
};
const onError = error => {
if (error.syscall !== "listen") {
throw error;
}
const bind = typeof port === "string" ? "pipe " + port : "port " + port;
switch (error.code) {
case "EACCES":
console.error(bind + " requires elevated privileges");
process.exit(1);
break;
case "EADDRINUSE":
console.error(bind + " is already in use");
process.exit(1);
break;
default:
throw error;
}
};
console.log("process.env.COSMODDB_USER");
console.log(env.COSMODDB_USER);
mongoose
.connect(
"mongodb://" +
process.env.COSMOSDB_HOST +
":" +
process.env.COSMOSDB_PORT +
"/" +
process.env.COSMOSDB_DBNAME +
"?ssl=true&replicaSet=globaldb",
{
auth: {
user: process.env.COSMODDB_USER,
password: process.env.COSMOSDB_PASSWORD
}
}
)
.then(() => console.log("Connection to CosmosDB successful"))
.catch(err => console.error(err));
const onListening = () => {
const addr = server.address();
const bind = typeof port === "string" ? "pipe " + port : "port " + port;
debug("Listening on " + bind);
};
const port = normalizePort(process.env.PORT || "3000");
app.set("port", process.env.PORT || port);
var server = app.listen(app.get("port"), function() {
debug("Express server listening on port " + server.address().port);
});
server.js in root directory (localhost:8080 CORS error)
var express = require('express');
var app = express();
var bodyParser = require('body-parser');
var morgan = require('morgan');
const userRoutes = require("./app/routes/user");
const appRoutes = require("./app/app");
const cors = require("cors");
app.use(morgan('dev'));
app.use(cors({ origin: 'http://localhost:8080' , credentials : true}));var mongoose = require('mongoose');
var path = require('path');
var config = 'mongodb://azure45:azure45#ds133321.mlab.com:33321/azure_chat'
//const app = require("./app");
const debug = require("debug")("node-angular");
var env = require("dotenv").config();
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
app.use(function(req, res, next) {
res.setHeader('Access-Control-Allow-Origin', '*');
res.setHeader('Access-Control-Allow-Methods', 'GET, POST');
next();
});
mongoose
.connect(
"mongodb://" +
process.env.COSMOSDB_HOST +
":" +
process.env.COSMOSDB_PORT +
"/" +
process.env.COSMOSDB_DBNAME +
"?ssl=true&replicaSet=globaldb",
{
auth: {
user: process.env.COSMODDB_USER,
password: process.env.COSMOSDB_PASSWORD
}
}
)
.then(() => console.log("Connection to CosmosDB successful"))
.catch(err => console.error(err));
app.use(express.static(__dirname + '/public/dist/glass/'));
//var apiRoutes = require('./app/app')(app, express);
app.use("/api/", appRoutes);
app.use("/api/user", userRoutes);
app.get('*', function(req, res) {
res.sendFile(path.join(__dirname + '/public/dist/glass/index.html'));
});
app.listen(8080);
console.log('Magic happens on port ' + 8080);
const normalizePort = val => {
var port = parseInt(val, 10);
if (isNaN(port)) {
e;
// named pipe
return val;
}
if (port >= 0) {
// port number
return port;
}
return false;
};
const onError = error => {
if (error.syscall !== "listen") {
throw error;
}
const bind = typeof port === "string" ? "pipe " + port : "port " + port;
switch (error.code) {
case "EACCES":
console.error(bind + " requires elevated privileges");
process.exit(1);
break;
case "EADDRINUSE":
console.error(bind + " is already in use");
process.exit(1);
break;
default:
throw error;
}
};
console.log("process.env.COSMODDB_USER");
console.log(env.COSMODDB_USER);
const onListening = () => {
const addr = server.address();
const bind = typeof port === "string" ? "pipe " + port : "port " + port;
debug("Listening on " + bind);
};
Here's the project file structure as a reference. app.js is where all my APIs are.

Answer 1

Try to use Node.js CORS library for CORS.
Something like below.
const express = require("express");
const cors = require("cors");
const app = express();
app.use(cors());

Answer 2

With reference to rise's answer:
Add options to cors method:
var corsOptions = {
origin: 'your client url',
optionsSuccessStatus: 200,
}
app.use(cors(corsOptions));