Function instrumentFetch

packages/core/src/instrument/fetch.ts:49–157

(onFetchResolved?: (response: Response) => void, skipNativeFetchCheck: boolean = false)

}

function instrumentFetch(onFetchResolved?: (response: Response) => void, skipNativeFetchCheck: boolean = false): void {
  if (skipNativeFetchCheck && !supportsNativeFetch()) {
    return;
  }

  fill(GLOBAL_OBJ, 'fetch', function (originalFetch: () => void): () => void {
    return function (...args: any[]): void {
      // We capture the error right here and not in the Promise error callback because Safari (and probably other
      // browsers too) will wipe the stack trace up to this point, only leaving us with this file which is useless.

      // NOTE: If you are a Sentry user, and you are seeing this stack frame,
      //       it means the error, that was caused by your fetch call did not
      //       have a stack trace, so the SDK backfilled the stack trace so
      //       you can see which fetch call failed.
      const virtualError = new Error();

      const { method, url } = parseFetchArgs(args);
      const handlerData: HandlerDataFetch = {
        args,
        fetchData: {
          method,
          url,
        },
        startTimestamp: timestampInSeconds() * 1000,
        // // Adding the error to be able to fingerprint the failed fetch event in HttpClient instrumentation
        virtualError,
        headers: getHeadersFromFetchArgs(args),
      };

      // if there is no callback, fetch is instrumented directly
      if (!onFetchResolved) {
        triggerHandlers('fetch', {
          ...handlerData,
        });
      }

      // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
      return originalFetch.apply(GLOBAL_OBJ, args).then(
        async (response: Response) => {
          if (onFetchResolved) {
            onFetchResolved(response);
          } else {
            triggerHandlers('fetch', {
              ...handlerData,
              endTimestamp: timestampInSeconds() * 1000,
              response,
            });
          }

          return response;
        },
        (error: Error) => {
          triggerHandlers('fetch', {
            ...handlerData,
            endTimestamp: timestampInSeconds() * 1000,
            error,
          });