Dispatch events on retries (#152)

source/events.ts

@@ -0,0 +1 @@
+export const events = new EventTarget();

source/index.ts

@@ -3,6 +3,7 @@
 export * from "./receiver.js";
 export * from "./sender.js";
 export * from "./types.js";
+export * from "./events.js";
 export { getThisFrame, getTopLevelFrame } from "./thisTarget.js";
 export { toggleLogging } from "./logging.js";
 

source/sender.ts

@@ -16,6 +16,7 @@ import { isObject, MessengerError, __webextMessenger } from "./shared.js";
 import { log } from "./logging.js";
 import { type SetReturnType } from "type-fest";
 import { handlers } from "./handlers.js";
+import { events } from "./events.js";
 
 const _errorNonExistingTarget =
   "Could not establish connection. Receiving end does not exist.";
@@ -116,6 +117,18 @@ async function manageMessage(
       factor: 1.3,
       maxRetryTime: 4000,
       async onFailedAttempt(error) {
+        events.dispatchEvent(
+          new CustomEvent("failed-attempt", {
+            detail: {
+              type,
+              seq,
+              target,
+              error,
+              attemptCount: error.attemptNumber,
+            },
+          })
+        );
+
         if (error.message === _errorTargetClosedEarly) {
           throw new Error(errorTargetClosedEarly);
         }
@@ -158,6 +171,12 @@ async function manageMessage(
       );
     }
 
+    events.dispatchEvent(
+      new CustomEvent("attempts-exhausted", {
+        detail: { type, seq, target, error },
+      })
+    );
+
     throw error;
   });