feat: add beacon request parameters hook

This change introduces a new hook called `resolveSendBeaconRequestParameters`. This enables consumers to modify a subset of the RequestInit parameters being used by the fetch request that polyfills the navigator.sendBeacon API in the worker context, e.g. setting keepalive: false

src/lib/types.ts

@@ -380,6 +380,11 @@ export type SerializedInstance =
  */
 export type ResolveUrlType = 'fetch' | 'xhr' | 'script' | 'iframe' | 'image';
 
+/**
+ * @public
+ */
+export type SendBeaconParameters = Pick<RequestInit, 'keepalive' | 'mode' | 'headers' | 'signal' | 'cache'>;
+
 /**
  * https://partytown.builder.io/configuration
  *
@@ -398,6 +403,15 @@ export interface PartytownConfig {
    * @returns The returned value must be a URL interface, otherwise the default resolved URL is used.
    */
   resolveUrl?(url: URL, location: Location, type: ResolveUrlType): URL | undefined | null;
+  /**
+   * The `resolveSendBeaconRequestParameters()` hook can be used to modify the RequestInit parameters
+   * being used by the fetch request that polyfills the navigator.sendBeacon API in the worker context.
+   *
+   * @param url - The URL to be resolved. This is a URL https://developer.mozilla.org/en-US/docs/Web/API/URL, not a string.
+   * @param location - The current window location.
+   * @returns The returned value must be a SendBeaconParameters interface, otherwise the default parameters are used.
+   */
+  resolveSendBeaconRequestParameters?(url: URL, location: Location): SendBeaconParameters | undefined | null;
   /**
    * When set to `true`, Partytown scripts are not inlined and not minified.
    *

src/lib/web-worker/worker-exec.ts

@@ -213,14 +213,7 @@ export const insertIframe = (winId: WinId, iframe: WorkerInstance) => {
   callback();
 };
 
-export const resolveToUrl = (
-  env: WebWorkerEnvironment,
-  url: string,
-  type: ResolveUrlType | null,
-  baseLocation?: Location,
-  resolvedUrl?: URL,
-  configResolvedUrl?: any
-) => {
+const resolveBaseLocation = (env: WebWorkerEnvironment, baseLocation?: Location) => {
   baseLocation = env.$location$;
   while (!baseLocation.host) {
     env = environments[env.$parentWinId$];
@@ -229,7 +222,20 @@ export const resolveToUrl = (
       break;
     }
   }
+  return baseLocation;
+}
 
+export const resolveToUrl = (
+  env: WebWorkerEnvironment,
+  url: string,
+  type: ResolveUrlType | null,
+  baseLocation?: Location,
+  resolvedUrl?: URL,
+  configResolvedUrl?: any
+) => {
+
+  baseLocation = resolveBaseLocation(env, baseLocation);
+
   resolvedUrl = new URL(url || '', baseLocation as any);
   if (type && webWorkerCtx.$config$.resolveUrl) {
     configResolvedUrl = webWorkerCtx.$config$.resolveUrl!(resolvedUrl, baseLocation, type!);
@@ -243,5 +249,17 @@ export const resolveToUrl = (
 export const resolveUrl = (env: WebWorkerEnvironment, url: string, type: ResolveUrlType | null) =>
   resolveToUrl(env, url, type) + '';
 
+export const resolveSendBeaconRequestParameters = (env: WebWorkerEnvironment, url: string) => {
+  const baseLocation = resolveBaseLocation(env);
+  const resolvedUrl = new URL(url || '', baseLocation as any);
+  if (webWorkerCtx.$config$.resolveSendBeaconRequestParameters) {
+    const configResolvedParams = webWorkerCtx.$config$.resolveSendBeaconRequestParameters!(resolvedUrl, baseLocation);
+    if (configResolvedParams) {
+      return configResolvedParams;
+    }
+  }
+  return {};
+}
+
 export const getPartytownScript = () =>
   `<script src="${partytownLibUrl('partytown.js?v=' + VERSION)}"></script>`;

src/lib/web-worker/worker-navigator.ts

@@ -1,7 +1,7 @@
 import type { WebWorkerEnvironment } from '../types';
 import { debug } from '../utils';
 import { logWorker } from '../log';
-import { resolveUrl } from './worker-exec';
+import { resolveSendBeaconRequestParameters, resolveUrl } from './worker-exec';
 import { webWorkerCtx } from './worker-constants';
 import { getter } from './worker-proxy';
 
@@ -25,6 +25,7 @@ export const createNavigator = (env: WebWorkerEnvironment) => {
           body,
           mode: 'no-cors',
           keepalive: true,
+          ...(resolveSendBeaconRequestParameters(env, url))
         });
         return true;
       } catch (e) {