fix: Handle default flush interval for browser SDK.

Author: kinyoklion

packages/sdk/browser/__tests__/options.test.ts

@@ -2,7 +2,7 @@ import { jest } from '@jest/globals';
 
 import { LDLogger } from '@launchdarkly/js-client-sdk-common';
 
-import validateOptions, { filterToBaseOptions } from '../src/options';
+import validateOptions, { filterToBaseOptions, withBrowserDefaults } from '../src/options';
 
 let logger: LDLogger;
 
@@ -50,7 +50,7 @@ it('warns for invalid configuration', () => {
   );
 });
 
-it('applies default options', () => {
+it('applies default browser-specific options', () => {
   const opts = validateOptions({}, logger);
 
   expect(opts.fetchGoals).toBe(true);
@@ -75,3 +75,23 @@ it('filters to base options', () => {
   expect(baseOpts).not.toHaveProperty('fetchGoals');
   expect(baseOpts).not.toHaveProperty('eventUrlTransformer');
 });
+
+it('applies default overrides to common config flushInterval', () => {
+  const opts = {};
+  const result = withBrowserDefaults(opts);
+  expect(result.flushInterval).toEqual(2);
+});
+
+it('does not override common config flushInterval if it is set', () => {
+  const opts = {
+    flushInterval: 15,
+  };
+  const result = withBrowserDefaults(opts);
+  expect(result.flushInterval).toEqual(15);
+});
+
+it('includes overridden defaults after filtering to base options', () => {
+  const opts = {};
+  const result = filterToBaseOptions(withBrowserDefaults(opts));
+  expect(result.flushInterval).toEqual(2);
+});

packages/sdk/browser/src/BrowserClient.ts

@@ -21,7 +21,11 @@ import { BrowserIdentifyOptions as LDIdentifyOptions } from './BrowserIdentifyOp
 import { registerStateDetection } from './BrowserStateDetector';
 import GoalManager from './goals/GoalManager';
 import { Goal, isClick } from './goals/Goals';
-import validateOptions, { BrowserOptions, filterToBaseOptions } from './options';
+import validateOptions, {
+  BrowserOptions,
+  filterToBaseOptions,
+  withBrowserDefaults,
+} from './options';
 import BrowserPlatform from './platform/BrowserPlatform';
 
 /**
@@ -116,13 +120,14 @@ export class BrowserClient extends LDClientImpl implements LDClient {
     const baseUrl = options.baseUri ?? 'https://clientsdk.launchdarkly.com';
 
     const platform = overridePlatform ?? new BrowserPlatform(logger);
-    const validatedBrowserOptions = validateOptions(options, logger);
+    const optionsWithDefaults = withBrowserDefaults(options);
+    const validatedBrowserOptions = validateOptions(optionsWithDefaults, logger);
     const { eventUrlTransformer } = validatedBrowserOptions;
     super(
       clientSideId,
       autoEnvAttributes,
       platform,
-      filterToBaseOptions({ ...options, logger }),
+      filterToBaseOptions({ ...optionsWithDefaults, logger }),
       (
         flagManager: FlagManager,
         configuration: Configuration,

packages/sdk/browser/src/options.ts

@@ -84,14 +84,14 @@ export function filterToBaseOptions(opts: BrowserOptions): LDOptionsBase {
   return baseOptions;
 }
 
-function applyBrowserDefaults(opts: BrowserOptions) {
-  // eslint-disable-next-line no-param-reassign
-  opts.flushInterval ??= DEFAULT_FLUSH_INTERVAL_SECONDS;
+export function withBrowserDefaults(opts: BrowserOptions): BrowserOptions {
+  const output = { ...opts };
+  output.flushInterval ??= DEFAULT_FLUSH_INTERVAL_SECONDS;
+  return output;
 }
 
 export default function validateOptions(opts: BrowserOptions, logger: LDLogger): ValidatedOptions {
   const output: ValidatedOptions = { ...optDefaults };
-  applyBrowserDefaults(output);
 
   Object.entries(validators).forEach((entry) => {
     const [key, validator] = entry as [keyof BrowserOptions, TypeValidator];