CORS Origin issues.

I'm trying to host one of my web applications on my raspberry but I keep running into CORS issues. I can reach the web application just fine from my computer, and I can input the url in the adress bar just fine (http:// ipadress :3000/getCards?cardName=dark%20magician ) and I get back the JSON that I'm expecting. But when using the web application itself which should send the request I keep running into CORS Origin issues. I tried: npm installing cors, requering it in my javascript and using app.use('cors') tried to explicitly declare the cors headers in my app.get route tried app.use(cors({ origin: '' })); tried

const corsOptions = {
  origin: 'http://ipadress:3000',
  methods: 'GET,HEAD,PUT,PATCH,POST,DELETE',
  credentials: true,
  optionsSuccessStatus: 204,
};

app.use(cors(corsOptions));

But nothing seems to work. these are the response headers in my browser:

GET /getCards?cardName=d undefined
Host: localhost:3000
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:121.0) Gecko/20100101 Firefox/121.0
Accept: /
Accept-Language: nl,en-US;q=0.7,en;q=0.3
Accept-Encoding: gzip, deflate, br
Referer: http://ipadress:3000/
Origin: http://ipadress*:3000
Connection: keep-alive
Sec-Fetch-Dest: empty
Sec-Fetch-Mode: cors
Sec-Fetch-Site: cross-site

I was hoping someone here might be able to help me who perhaps has run into these issues before.

Try reaching out for help in other servers, as this one might not be that in depth with web servers and such.