post request to Express.js api from another computer - node.js

Question

I have a server running on localhost:3000, and I set my app.js to use the angular router when I try to access localhost:3000 in my browser
(example :app.use('/', express.static(path.join(__dirname, '/dist/Client')));)
When I make a post request to my api I do:
const headers = new Headers({
'Content-Type': 'application/json'
});
const options = new RequestOptions({
headers: headers
});
this.http.post('http://localhost:3000/api/someAction',{body},options)
.toPromise()
.then(//function)
Untill now everything is correct, but how can I make my server accessible from another computer. For example if another computer on the same network knows the private IP address of the server I want him to be able to access my app when he navigate to for example 192.168.1.10:3000. Right now I can access but all my http requests fail and I have the following error
Access to XMLHttpRequest at 'http://localhost:3000/api/someFunction'
from origin 'http://192.168.1.10:3000' has been blocked by CORS policy:
Response to preflight request doesn't pass access control check: It does not
have HTTP ok status.
In app.js I have the following:
app.use(function(req, res, next) {
res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
res.header("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS");
next();
});

Answer 1

This is a CORS error message you're getting.
You can use the Express CORS middleware to allow calls from other origins to your server. Make sure to choose the right options to allow calls from your other PC.
https://expressjs.com/en/resources/middleware/cors.html
And also make sure to place the CORS middleware at the top of your application definition.
const app = express();
app.use(cors({ origin: "*" })); // Do this first
//... the rest of your routes and handlers and middlewares
From your local machine where things seem to work correctly, open your Chrome Dev Tools, and make sure OPTION calls are being made and fulfilled successfully, and that proper headers are being returned.
Lastly, from a security perspective, remove or restrict the CORS options as much as possible for your production environment. Only use flexible CORS policy during development and testing.