feat(core): Add beforeStartNavigationSpan lifecycle hook

Author: Lms24

packages/browser/src/tracing/browserTracingIntegration.ts

@@ -609,6 +609,7 @@ export function startBrowserTracingPageLoadSpan(
  * This will only do something if a browser tracing integration has been setup.
  */
 export function startBrowserTracingNavigationSpan(client: Client, spanOptions: StartSpanOptions): Span | undefined {
+  client.emit('beforeStartNavigationSpan', spanOptions);
   client.emit('startNavigationSpan', spanOptions);
 
   getCurrentScope().setTransactionName(spanOptions.name);

packages/browser/test/tracing/browserTracingIntegration.test.ts

@@ -788,6 +788,24 @@ describe('browserTracingIntegration', () => {
         },
       });
     });
+
+    it('triggers beforeStartNavigationSpan hook listeners', () => {
+      const client = new BrowserClient(
+        getDefaultBrowserClientOptions({
+          tracesSampleRate: 1,
+          integrations: [browserTracingIntegration()],
+        }),
+      );
+      setCurrentClient(client);
+
+      const mockBeforeStartNavigationSpanCallback = vi.fn((options: StartSpanOptions) => options);
+
+      client.on('beforeStartNavigationSpan', mockBeforeStartNavigationSpanCallback);
+
+      startBrowserTracingNavigationSpan(client, { name: 'test span', op: 'navigation' });
+
+      expect(mockBeforeStartNavigationSpanCallback).toHaveBeenCalledWith({ name: 'test span', op: 'navigation' });
+    });
   });
 
   describe('using the <meta> tag data', () => {

packages/core/src/client.ts

@@ -603,6 +603,12 @@ export abstract class Client<O extends ClientOptions = ClientOptions> {
     ) => void,
   ): () => void;
 
+  /**
+   * A hook for triggering right before a navigation span is started.
+   * @returns {() => void} A function that, when executed, removes the registered callback.
+   */
+  public on(hook: 'beforeStartNavigationSpan', callback: (options: StartSpanOptions) => void): () => void;
+
   /**
    * A hook for browser tracing integrations to trigger a span for a navigation.
    * @returns {() => void} A function that, when executed, removes the registered callback.
@@ -779,6 +785,11 @@ export abstract class Client<O extends ClientOptions = ClientOptions> {
     traceOptions?: { sentryTrace?: string | undefined; baggage?: string | undefined },
   ): void;
 
+  /**
+   * Emit a hook event for triggering right before a navigation span is started.
+   */
+  public emit(hook: 'beforeStartNavigationSpan', options: StartSpanOptions): void;
+
   /**
    * Emit a hook event for browser tracing integrations to trigger a span for a navigation.
    */