CORS express not working predictably

Question

I am trying to allow access from everywhere.

I have tried using app middleware:

app.use(function (req, res, next) {
  res.setHeader(\"Access-Control-Allo         


        

Answer 1

MDN has a very short explanation on how a server should respond to a Preflight Request.

You handle CORS preflight requests by handling the HTTP OPTIONS method (just like you would handle GET and POST methods) before handling other request methods on the same route:

app.options('/login', ...);
app.get('/login'. ...);
app.post('/login'. ...);

In your case, it might be as simple as changing your app.use() call to app.options(), passing the route as the first argument, setting the appropriate headers, then ending the response:

app.options('/login', function (req, res) {
  res.setHeader("Access-Control-Allow-Origin", "*");
  res.setHeader('Access-Control-Allow-Methods', '*');
  res.setHeader("Access-Control-Allow-Headers", "*");
  res.end();
});
app.post('/login', function (req, res) {
  ...
});

Answer 2

Following other's answers, this worked for me:

res.setHeader("Access-Control-Allow-Origin", 'http://myDomain:8080');
res.setHeader('Access-Control-Allow-Methods', 'POST,GET,OPTIONS,PUT,DELETE');
res.setHeader('Access-Control-Allow-Headers', 'Content-Type,Accept');

Answer 3

Following some standard node projects out there, below CORS configuration worked for me always. It requires the npm package 'cors'. Note: Origin * means enabling responses to any origin and replies with status code 200. If this needs to be limited to one domain, update the origin accordingly. Ex: [origin: 'http://exampleui.com']

var cors = require('cors');
var corsOptions = {
    origin: '*',
    optionsSuccessStatus: 200,
  }
app.use(cors(corsOptions));
app.use(express.json())

Answer 4

First install, the "cors" package from npm: npm i -S cors

Then enable it in your express server.

var express = require('express'),
  cors = require('cors');

const app = express();
app.use(cors());

...

Answer 5

Configure the CORS stuff before your routes, not inside them.

Here, like this (from enable-cors.org):

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");
  next();
});

app.get('/', function(req, res, next) {
  // Handle the get for this route
});

app.post('/', function(req, res, next) {
 // Handle the post for this route
});

I always configure it like this in my Express+Angular apps and it works just fine.

Hope it helps.

Answer 6

After applying "cors" middleware. You should be passed "http://" before "localhost:". in url send to by Axios like this:

axios.get("http://localhost:8080/api/getData")
.then(function (response) {
this.items= response.data;
}).catch(function (error) {
console.log(error)
});