To avoid dropping AJAX calls when an OAuth access token expires, you can implement a mechanism to automatically refresh the access token before making the AJAX call. This approach ensures that the access token is always valid when sending requests to the API server. Here's a step-by-step guide to achieve this:

  1. Token Expiry Tracking: Keep track of the access token's expiry time either in memory or through local storage (Web Storage). The token's expiry time is typically provided in the response when you initially request the access token from the OAuth provider.

  2. Automatic Token Refresh: Before making an AJAX call, check if the access token has expired or is about to expire (e.g., within a certain threshold time, like 5 minutes). If the token has expired, trigger an automatic token refresh.

  3. Token Refresh Endpoint: Create a server-side endpoint on your backend that handles token refresh requests. This endpoint should accept the expired access token and return a new, valid access token.

  4. AJAX Interceptor: Implement an AJAX interceptor in your JavaScript code that intercepts all outgoing AJAX requests. In the interceptor, check the token's expiry status. If it's expired, trigger the token refresh and update the access token in the request header before proceeding with the AJAX call.

  5. Token Refresh Flow: When triggering the token refresh, send the expired access token to your backend's token refresh endpoint. The backend should verify the token's validity, and if valid, issue a new access token and return it as the response.

  6. Update Access Token: Once you receive the new access token from the token refresh endpoint, update the stored access token (either in memory or local storage) with the new token and proceed with the original AJAX call.

Here's a simplified example of how you can implement the automatic token refresh in JavaScript:

javascript
// Function to check if the access token has expired function isTokenExpired() { const accessTokenExpiration = localStorage.getItem('access_token_expiration'); return Date.now() > accessTokenExpiration; } // Function to refresh the access token async function refreshToken() { const expiredAccessToken = localStorage.getItem('access_token'); // Call your server-side token refresh endpoint const response = await fetch('/api/token-refresh', { method: 'POST', headers: { Authorization: `Bearer ${expiredAccessToken}`, }, }); const data = await response.json(); const newAccessToken = data.access_token; const newAccessTokenExpiration = Date.now() + data.expires_in * 1000; // Convert expires_in to milliseconds // Update the access token and its expiration time localStorage.setItem('access_token', newAccessToken); localStorage.setItem('access_token_expiration', newAccessTokenExpiration); return newAccessToken; } // AJAX interceptor axios.interceptors.request.use(async (config) => { if (isTokenExpired()) { try { const newAccessToken = await refreshToken(); config.headers.Authorization = `Bearer ${newAccessToken}`; } catch (error) { // Handle token refresh error console.error('Error refreshing token:', error); throw error; // Rethrow the error to stop the AJAX request } } return config; }); // Example AJAX call axios.get('/api/data') .then((response) => { // Handle the AJAX response }) .catch((error) => { // Handle AJAX error console.error('AJAX Error:', error); });

Note: The example uses Axios as the AJAX library, but you can adapt this to any other library you are using (e.g., jQuery's $.ajax, Fetch API, etc.).

By implementing this automatic token refresh mechanism, your AJAX calls won't be dropped due to an expired access token, and you can maintain a seamless user experience with continuous access to the API resources.

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