Fetch API cannot load, cors - reactjs

Question

In my React app I am trying to make a GET request from my heroku server to get a list of users:
https://blablabla.heroku.com/users
using the following request:
const sendSearch = fetch('/https://blablabla.heroku.com/users', {credentials: 'same-origin'})
function loadMyUsers(data) {
data.json().then((jsonData) => {
// console.log(jsonData)
})
}
sendSearch.then(loadMyUsers)}
However I get the following error:
Fetch API cannot load https://blablabla.heroku.com/users.
Response to preflight request doesn't pass access control check: No
'Access-Control-Allow-Origin' header is present on the requested
resource. Origin 'http://localhost:8080' is therefore not allowed
access. If an opaque response serves your needs, set the request's mode
to 'no-cors' to fetch the resource with CORS disabled.
I tried changing my Fetch method to many things similar to:
const sendSearch = fetch('https://blablabla.heroku.com/users',{
method: 'GET',
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json',
'mode': 'no-cors'
}
})
but the problem persists.
How do I make the cross domain request?

Answer 1

On your heroku server you should add Access-Control-Allow-Origin: * to your response headers, or more specific Access-Control-Allow-Origin: http://localhost:8080 if you wish.
On your production server though, you probably won't need this header, unless you have very good reason for cross origin requests.