Prevent Multiple Token Refreshes With API React Hook - reactjs

Question

I have an API hook called useAPICall that has a callback call. This callback checks if a token stored in a reactn variable called auth is expired, refreshes it if necessary, then calls the fetch function.
I call it in my component like this:
const [api] = useAPICall();
useEffect(() => {
api.call('/api/settings/mine/').then(data => {
// do stuff here
});
}, []);
And it does work. It goes through the authentication flow and calls the API. But if I have useAPICall is multiple components that all try to call the API around the same time (such as a cold page load), then each instance of it calls the refresh token method because it's expired.
The auth info (access/refresh tokens) are stored in a reactn global variable auth such as below, inside the useAPICall.js hook
import React, {useCallback, useContext, useEffect, useMemo, useState} from 'react';
import {useDispatch, useGlobal} from 'reactn';
export function useAPICall() {
const [auth, setAuth] = useGlobal('auth');
const authRefreshSuccess = useDispatch('authRefreshSuccess');
async function refreshToken() {
console.log('Refreshing access token...');
const authResponse = await fetch('/api/auth/token/refresh/', {
method: 'POST',
credentials: 'same-origin',
body: JSON.stringify({refresh: auth.refresh.token}),
headers: {
'Content-Type': 'application/json',
},
});
if (authResponse.ok) {
const authToken = await authResponse.json();
await authRefreshSuccess(authToken);
return authToken.access;
}
}
function isTokenExpired() {
if (localAuth.access)
return auth.access.exp <= Math.floor(Date.now() / 1000);
else
return false;
}
const call = useCallback(async (endpoint, options={headers: {}}) => {
console.log('performing api call');
token = undefined;
if (isTokenExpired())
token = await refreshToken();
else
token = localAuth.access.token;
const res = await fetch(endpoint, {
...options,
headers: {
...options.headers,
'Authorization': `Bearer ${token}`,
}
});
if (!res.ok)
throw await res.json();
return res.json();
}, []);
const anonCall = useCallback(async (endpoint, options={}}) => {
const res = await fetch(endpoint, options);
if (!res.ok)
throw await res.json();
return res.json();
}, []);
const api = useMemo(
() => ({
call,
anonCall,
}),
[call, anonCall,]
);
return [api]
}
How can I prevent them from firing off the refresh method multiple times?
If there's a better way (without redux) to have a universal API flow (where any API call would first check access token and refresh if necessary), then I'm willing to listen.

Answer 1

I managed to do this by storing a promise in a global variable.
let refreshPromise = null;
export function useAuthentication() {
async function getBearer() {
if (isExpired(jwt)) {
if (refreshPromise == null) {
refreshPromise = refresh().then((jwt) => {
refreshPromise = null;
return jwt;
});
}
await refreshPromise;
}
let authData = getAuthData();
if (authData && authData.accessToken) {
return `Bearer ${authData.accessToken}`;
}
return null;
}
const AuthenticationService = {
getBearer,
...
};
return AuthenticationService;
}
Hope this helps !