CORs error when accessing Square V2 API - laravel

Question

I'm making a client-side request out to V2 of the Square API using Vue and Axios. My Vue component is as follows:
import axios from 'axios';
export default {
mounted() {
var instance = axios.create({
baseURL: 'https://connect.squareup.com/v2/',
timeout: 1000,
headers: {
'Authorization': 'Bearer xxxxxxxxxxxxxxxxx',
'Accepts': 'application/json',
'Content-Type': 'application/json'
}
});
instance.get('catalog/list')
.then(function (response) {
console.log(response);
}) ;
}
}
However, when I make that call, I receive the following error:
Failed to load https://connect.squareup.com/v2/catalog/list: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'https://local-env.dev' is therefore not allowed access. The response had HTTP status code 403.
That error suggests that there is some configuration that has to happen on the Square side, but I saw no opportunity to whitelist domains, etc.
Has anyone come across this error before, regardless of service, and if so, how did you resolve?

Answer 1

I don't think the Square API supports being called from a browser. I used Postman to do an OPTIONS request on https://connect.squareup.com/v2/catalog/list and the response was a NOT_FOUND. The OPTIONS request is needed for proper CORS support.
Plus, if you did this, I would think your auth token would need to be sent to the client -- thus exposing it to everyone. It looks like the Square API is only designed to be called from a server. But that is just based on me skimming the docs a bit. I have no experience using their API.

Answer 2

When doing OAuth authorization request you are not supposed to do it from your application. Create and URL with the parameters and open it in a new browser window or tab, Something like:
const grants='MERCHANT_PROFILE_READ CUSTOMERS_READ CUSTOMERS_WRITE PAYMENTS_READ PAYMENTS_WRITE PAYMENTS_WRITE_ADDITIONAL_RECIPIENTS PAYMENTS_WRITE_IN_PERSON';
const params = new HttpParams()
.set('scope', grants)
.set('client_id', <YourSquareApplicationId>)
.set('state', '1878789');
const requestUrl = `${<squareUrl>}/oauth2/authorize?${params.toString()}`;
window.open(requestUrl, "_blank");
That new window is supposed to ask the end user to login to his account and accept or deny the request.