Firebase Fetch - No Access-Control-Allow-Origin

Question

I'm developing an app with `React + Redux` and I have my `JSON` database within a `Firebase` DB. To do this I'm tryin to `fetch` my data from a valid URL (validated from Firebase simulator) ``` let firebase = 'https://******.firebaseio.com/**/*/***/*' return (dispatch) => { return fetch(firebase) .then(res => res.json()) .then(json => dispatch({ type: 'GET_JSON', payload: json })) } ``` This returns to me the error: Fetch API cannot load https://console.firebase.google.com/project/****/database/data/**/*/***/*. Redirect from 'https://console.firebase.google.com/project//database/data/**///' to 'https://accounts.google.com/ServiceLogin?ltmpl=firebase&osid=1&passive=true…ole.firebase.google.com/project//database/data///**/' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' 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…

Accepted Answer

```
likely error that arise to  cors blocked when using firebase is
when you initiate a put or get request with an incomplete firebase url
e.g
// wrong form
 this.http.get('https://******.firebaseio.com/data')   //this will throw an exception

// correct form                                                    
  this.http.get('https://******.firebaseio.com/data.json')
```

Firebase Fetch - No Access-Control-Allow-Origin

Solution

Problem