fix(otlp-exporter-base): remove xhr transport

experimental/CHANGELOG.md

@@ -8,6 +8,9 @@ For notes on migrating to 2.x / 0.200.x see [the upgrade guide](doc/upgrade-to-2
 
 ### :boom: Breaking Changes
 
+* fix(otlp-exporter-base)!: remove xhr transport [#6317](https://github.com/open-telemetry/opentelemetry-js/pull/6317) @cjihrig
+  * (user-facing) The deprecated XHR-based transport has been removed and replaced with `fetch()`. This change affects users who relied on `XmlHttpRequest` instead of `fetch()` for sending headers with OTLP exports. To maintain compatibility on browsers without a `fetch()` implementation, include a `fetch()` polyfill.
+
 ### :rocket: Features
 
 * feat(sdk-logs): export event name from ConsoleLogRecordExporter [#6310](https://github.com/open-telemetry/opentelemetry-js/pull/6310) @aicest

experimental/packages/otlp-exporter-base/src/configuration/create-legacy-browser-delegate.ts

@@ -17,7 +17,6 @@ import { ISerializer } from '@opentelemetry/otlp-transformer';
 import {
   createOtlpFetchExportDelegate,
   createOtlpSendBeaconExportDelegate,
-  createOtlpXhrExportDelegate,
 } from '../otlp-browser-http-export-delegate';
 import { convertLegacyBrowserHttpOptions } from './convert-legacy-browser-http-options';
 import { IOtlpExportDelegate } from '../otlp-export-delegate';
@@ -52,9 +51,7 @@ export function inferExportDelegateToUse(
 ) {
   if (!configHeaders && typeof navigator.sendBeacon === 'function') {
     return createOtlpSendBeaconExportDelegate;
-  } else if (typeof globalThis.fetch !== 'undefined') {
-    return createOtlpFetchExportDelegate;
-  } else {
-    return createOtlpXhrExportDelegate;
   }
+
+  return createOtlpFetchExportDelegate;
 }

experimental/packages/otlp-exporter-base/src/index-browser-http.ts

@@ -14,10 +14,7 @@
  * limitations under the License.
  */
 
-export {
-  createOtlpXhrExportDelegate,
-  createOtlpSendBeaconExportDelegate,
-} from './otlp-browser-http-export-delegate';
+export { createOtlpSendBeaconExportDelegate } from './otlp-browser-http-export-delegate';
 
 export { convertLegacyBrowserHttpOptions } from './configuration/convert-legacy-browser-http-options';
 export { createLegacyOtlpBrowserExportDelegate } from './configuration/create-legacy-browser-delegate';

experimental/packages/otlp-exporter-base/src/otlp-browser-http-export-delegate.ts

@@ -17,27 +17,10 @@ import { OtlpHttpConfiguration } from './configuration/otlp-http-configuration';
 import { ISerializer } from '@opentelemetry/otlp-transformer';
 import { IOtlpExportDelegate } from './otlp-export-delegate';
 import { createRetryingTransport } from './retrying-transport';
-import { createXhrTransport } from './transport/xhr-transport';
 import { createSendBeaconTransport } from './transport/send-beacon-transport';
 import { createOtlpNetworkExportDelegate } from './otlp-network-export-delegate';
 import { createFetchTransport } from './transport/fetch-transport';
 
-/**
- * @deprecated use {@link createOtlpFetchExportDelegate}
- */
-export function createOtlpXhrExportDelegate<Internal, Response>(
-  options: OtlpHttpConfiguration,
-  serializer: ISerializer<Internal, Response>
-): IOtlpExportDelegate<Internal> {
-  return createOtlpNetworkExportDelegate(
-    options,
-    serializer,
-    createRetryingTransport({
-      transport: createXhrTransport(options),
-    })
-  );
-}
-
 export function createOtlpFetchExportDelegate<Internal, Response>(
   options: OtlpHttpConfiguration,
   serializer: ISerializer<Internal, Response>

experimental/packages/otlp-exporter-base/test/browser/create-legacy-browser-delegate.test.ts

@@ -19,7 +19,6 @@ import { inferExportDelegateToUse } from '../../src/configuration/create-legacy-
 import {
   createOtlpFetchExportDelegate,
   createOtlpSendBeaconExportDelegate,
-  createOtlpXhrExportDelegate,
 } from '../../src/otlp-browser-http-export-delegate';
 
 describe('createLegacyBrowserDelegate', function () {
@@ -51,43 +50,5 @@ describe('createLegacyBrowserDelegate', function () {
         assert.equal(delegate, createOtlpFetchExportDelegate);
       });
     });
-
-    describe('when fetch is unavailable', function () {
-      const fetch = window.fetch;
-      beforeEach(function () {
-        // fake fetch being unavailable
-        (window as any).fetch = undefined;
-      });
-      afterEach(() => {
-        window.fetch = fetch;
-      });
-
-      it('uses xhr delegate', function () {
-        const delegate = inferExportDelegateToUse(undefined);
-        assert.equal(delegate, createOtlpXhrExportDelegate);
-      });
-    });
-  });
-
-  describe('when fetch is unavailable but beacon and xhr are', function () {
-    const fetch = window.fetch;
-    beforeEach(function () {
-      // fake fetch being unavailable
-      (window as any).fetch = undefined;
-    });
-    afterEach(function () {
-      window.fetch = fetch;
-    });
-
-    it('uses xhr when beacon is available but headers are provided', function () {
-      const fetch = window.fetch;
-      // @ts-expect-error one should not be able to mutate the window but this is a test.
-      window.fetch = undefined;
-
-      const delegate = inferExportDelegateToUse({ foo: 'bar' });
-      assert.equal(delegate, createOtlpXhrExportDelegate);
-
-      window.fetch = fetch;
-    });
   });
 });