feat: add support for onRetryAttempt handler

README.md

@@ -51,15 +51,25 @@ const res = await axios({
   raxConfig: {
     // Retry 3 times before giving up.  Defaults to 3.
     retry: 3,
+
     // Milliseconds to delay at first.  Defaults to 100.
     retryDelay: 100,
+
     // # HTTP methods to automatically retry.  Defaults to:
     // ['GET', 'HEAD', 'OPTIONS', 'DELETE', 'PUT']
     httpMethodsToRetry: ['GET', 'HEAD', 'OPTIONS', 'DELETE', 'PUT'],
+
     // The response status codes to retry.  Supports a double
     // array with a list of ranges.  Defaults to:
     // [[100, 199], [429, 429], [500, 599]]
     httpStatusCodesToRetry: [[100, 199], [429, 429], [500, 599]],
+
+    // You can detect when a retry is happening, and figure out how many
+    // retry attempts have been made
+    onRetryAttempt: (err) => {
+      const cfg = rax.getConfig(err);
+      console.log(`Retry attempt #${cfg.currentRetryAttempt}`);
+    }
   }
 });
 ```

src/index.ts

@@ -35,6 +35,11 @@ export interface RetryConfig {
    * Defaults to: [[100, 199], [429, 429], [500, 599]]
    */
   statusCodesToRetry?: number[][];
+
+  /**
+   * Function to invoke when a retry attempt is made.
+   */
+  onRetryAttempt?: (err: AxiosError) => void;
 }
 
 export type RaxConfig = {
@@ -135,8 +140,15 @@ function onError(err: AxiosError) {
     setTimeout(resolve, delay);
   });
 
-  // Return the promise in which recalls axios to retry the request
+  // Put the config back into the err
   (err.config as RaxConfig).raxConfig = config;
+
+  // Notify the user if they added an `onRetryAttempt` handler
+  if (config.onRetryAttempt) {
+    config.onRetryAttempt(err);
+  }
+
+  // Return the promise in which recalls axios to retry the request
   return backoff.then(() => {
     return config.instance!.request(err.config);
   });

test/index.ts

@@ -2,6 +2,7 @@ import * as assert from 'assert';
 import axios, {AxiosError} from 'axios';
 import * as nock from 'nock';
 import * as rax from '../src';
+import {RaxConfig, RetryConfig} from '../src';
 
 const url = 'http://test.local';
 
@@ -129,4 +130,23 @@ describe('retry-axios', () => {
       assert.equal(0, cfg!.currentRetryAttempt);
     }
   });
+
+  it('should notify on retry attempts', async () => {
+    nock(url).get('/').reply(500);
+    nock(url).get('/').reply(200, 'toast');
+    interceptorId = rax.attach();
+    let flipped = false;
+    const config: RaxConfig = {
+      url,
+      raxConfig: {
+        onRetryAttempt: (err) => {
+          const cfg = rax.getConfig(err);
+          assert.equal(cfg!.currentRetryAttempt, 1);
+          flipped = true;
+        }
+      }
+    };
+    const res = await axios(config);
+    assert.equal(flipped, true);
+  });
 });