fix(replay): Capture JSON XHR response bodies

packages/browser-integration-tests/suites/replay/extendNetworkBreadcrumbs/xhr/captureResponseBody/test.ts

@@ -178,6 +178,93 @@ sentryTest('captures JSON response body', async ({ getLocalTestPath, page, brows
   ]);
 });
 
+sentryTest('captures JSON response body when responseType=json', async ({ getLocalTestPath, page, browserName }) => {
+  // These are a bit flaky on non-chromium browsers
+  if (shouldSkipReplayTest() || browserName !== 'chromium') {
+    sentryTest.skip();
+  }
+
+  await page.route('**/foo', route => {
+    return route.fulfill({
+      status: 200,
+      body: JSON.stringify({ res: 'this' }),
+      headers: {
+        'Content-Length': '',
+      },
+    });
+  });
+
+  await page.route('https://dsn.ingest.sentry.io/**/*', route => {
+    return route.fulfill({
+      status: 200,
+      contentType: 'application/json',
+      body: JSON.stringify({ id: 'test-id' }),
+    });
+  });
+
+  const requestPromise = waitForErrorRequest(page);
+  const replayRequestPromise1 = waitForReplayRequest(page, 0);
+
+  const url = await getLocalTestPath({ testDir: __dirname });
+  await page.goto(url);
+
+  void page.evaluate(() => {
+    /* eslint-disable */
+    const xhr = new XMLHttpRequest();
+
+    xhr.open('POST', 'http://localhost:7654/foo');
+    // Setting this to json ensures that xhr.response returns a POJO
+    xhr.responseType = 'json';
+    xhr.send();
+
+    xhr.addEventListener('readystatechange', function () {
+      if (xhr.readyState === 4) {
+        // @ts-expect-error Sentry is a global
+        setTimeout(() => Sentry.captureException('test error', 0));
+      }
+    });
+    /* eslint-enable */
+  });
+
+  const request = await requestPromise;
+  const eventData = envelopeRequestParser(request);
+
+  expect(eventData.exception?.values).toHaveLength(1);
+
+  expect(eventData?.breadcrumbs?.length).toBe(1);
+  expect(eventData!.breadcrumbs![0]).toEqual({
+    timestamp: expect.any(Number),
+    category: 'xhr',
+    type: 'http',
+    data: {
+      method: 'POST',
+      response_body_size: 14,
+      status_code: 200,
+      url: 'http://localhost:7654/foo',
+    },
+  });
+
+  const replayReq1 = await replayRequestPromise1;
+  const { performanceSpans: performanceSpans1 } = getCustomRecordingEvents(replayReq1);
+  expect(performanceSpans1.filter(span => span.op === 'resource.xhr')).toEqual([
+    {
+      data: {
+        method: 'POST',
+        statusCode: 200,
+        response: {
+          size: 14,
+          headers: {},
+          body: { res: 'this' },
+        },
+      },
+      description: 'http://localhost:7654/foo',
+      endTimestamp: expect.any(Number),
+      op: 'resource.xhr',
+      startTimestamp: expect.any(Number),
+    },
+  ]);
+});
+
 sentryTest('captures non-text response body', async ({ getLocalTestPath, page, browserName }) => {
   // These are a bit flaky on non-chromium browsers
   if (shouldSkipReplayTest() || browserName !== 'chromium') {

packages/replay/src/coreHandlers/util/networkUtils.ts

@@ -75,14 +75,18 @@ export function getBodyString(body: unknown): [string | undefined, NetworkMetaWa
     if (body instanceof FormData) {
       return [_serializeFormData(body)];
     }
+
+    if (!body) {
+      return [undefined];
+    }
   } catch {
     DEBUG_BUILD && logger.warn('[Replay] Failed to serialize body', body);
     return [undefined, 'BODY_PARSE_ERROR'];
   }
 
   DEBUG_BUILD && logger.info('[Replay] Skipping network body because of body type', body);
 
-  return [undefined];
+  return [undefined, 'UNPARSEABLE_BODY_TYPE'];
 }
 
 /** Merge a warning into an existing network request/response. */

packages/replay/src/coreHandlers/util/xhrUtils.ts

@@ -61,7 +61,7 @@ export function enrichXhrBreadcrumb(
   const reqSize = getBodySize(input, options.textEncoder);
   const resSize = xhr.getResponseHeader('content-length')
     ? parseContentLengthHeader(xhr.getResponseHeader('content-length'))
-    : getBodySize(xhr.response, options.textEncoder);
+    : _getBodySize(xhr.response, xhr.responseType, options.textEncoder);
 
   if (reqSize !== undefined) {
     breadcrumb.data.request_body_size = reqSize;
@@ -154,8 +154,7 @@ function _getXhrResponseBody(xhr: XMLHttpRequest): [string | undefined, NetworkM
 
   // Try to manually parse the response body, if responseText fails
   try {
-    const response = xhr.response;
-    return getBodyString(response);
+    return _parseXhrResponse(xhr.response, xhr.responseType);
   } catch (e) {
     errors.push(e);
   }
@@ -164,3 +163,57 @@ function _getXhrResponseBody(xhr: XMLHttpRequest): [string | undefined, NetworkM
 
   return [undefined];
 }
+
+/**
+ * Get the string representation of the XHR response.
+ * Based on MDN, these are the possible types of the response:
+ * string
+ * ArrayBuffer
+ * Blob
+ * Document
+ * POJO
+ *
+ * Exported only for tests.
+ */
+export function _parseXhrResponse(
+  body: XMLHttpRequest['response'],
+  responseType: XMLHttpRequest['responseType'],
+): [string | undefined, NetworkMetaWarning?] {
+  try {
+    if (typeof body === 'string') {
+      return [body];
+    }
+
+    if (body instanceof Document) {
+      return [body.body.outerHTML];
+    }
+
+    if (responseType === 'json' && body && typeof body === 'object') {
+      return [JSON.stringify(body)];
+    }
+
+    if (!body) {
+      return [undefined];
+    }
+  } catch {
+    __DEBUG_BUILD__ && logger.warn('[Replay] Failed to serialize body', body);
+    return [undefined, 'BODY_PARSE_ERROR'];
+  }
+
+  __DEBUG_BUILD__ && logger.info('[Replay] Skipping network body because of body type', body);
+
+  return [undefined, 'UNPARSEABLE_BODY_TYPE'];
+}
+
+function _getBodySize(
+  body: XMLHttpRequest['response'],
+  responseType: XMLHttpRequest['responseType'],
+  textEncoder: TextEncoder | TextEncoderInternal,
+): number | undefined {
+  try {
+    const bodyStr = responseType === 'json' && body && typeof body === 'object' ? JSON.stringify(body) : body;
+    return getBodySize(bodyStr, textEncoder);
+  } catch {
+    return undefined;
+  }
+}

packages/replay/src/types/request.ts

@@ -3,7 +3,12 @@ type JsonArray = unknown[];
 
 export type NetworkBody = JsonObject | JsonArray | string;
 
-export type NetworkMetaWarning = 'MAYBE_JSON_TRUNCATED' | 'TEXT_TRUNCATED' | 'URL_SKIPPED' | 'BODY_PARSE_ERROR';
+export type NetworkMetaWarning =
+  | 'MAYBE_JSON_TRUNCATED'
+  | 'TEXT_TRUNCATED'
+  | 'URL_SKIPPED'
+  | 'BODY_PARSE_ERROR'
+  | 'UNPARSEABLE_BODY_TYPE';
 
 interface NetworkMeta {
   warnings?: NetworkMetaWarning[];