feat: expose setConnectionMode on browser SDK by kinyoklion · Pull Request #1232 · launchdarkly/js-core

kinyoklion · 2026-03-27T21:53:50Z

Summary

Adds setConnectionMode(mode?: FDv2ConnectionMode) to the browser SDK's LDClient interface as an EAP method, giving users direct control over the connection mode with higher priority than setStreaming
Introduces BrowserDataSystemOptions type that restricts automaticModeSwitching to false | ManualModeSwitching only, removing the automatic option which has no impact for the browser SDK
Adds optional setConnectionMode to the shared DataManager interface following the same pattern as setForcedStreaming
Adds connection mode control buttons to the FDv2 example app for testing all modes

Note

Medium Risk
Medium risk because it adds a new (experimental) client API that can override connection behavior and wires through to FDv2-only data managers; incorrect use could alter flag update/connection semantics.

Overview
Adds an experimental LDClient.setConnectionMode(mode?: FDv2ConnectionMode) to the browser SDK, wiring it through BrowserClient to an optional DataManager.setConnectionMode implementation with validation and warnings when FDv2 isn’t enabled.

Introduces BrowserDataSystemOptions (exported from the package) to constrain browser dataSystem.automaticModeSwitching to false | ManualModeSwitching, and updates the FDv2 example app with UI controls to force/clear connection mode overrides for testing.

^{Written by Cursor Bugbot for commit 52eafe2. This will update automatically on new commits. Configure here.}

github-actions · 2026-03-27T21:55:18Z

@launchdarkly/js-sdk-common size report
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github-actions · 2026-03-27T21:55:42Z

@launchdarkly/browser size report
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Uncompressed size: 829227 bytes

github-actions · 2026-03-27T21:55:45Z

@launchdarkly/js-client-sdk-common size report
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github-actions · 2026-03-27T22:42:21Z

@launchdarkly/js-client-sdk size report
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Compressed size: 31556 bytes
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Uncompressed size: 112044 bytes

…mode switching Remove the automatic connection mode option from the browser SDK's public interface since it has no impact. Add setConnectionMode as an EAP method on the browser LDClient, giving users direct control over the connection mode with higher priority than setStreaming.

Add a Connection Mode control section with buttons for each FDv2ConnectionMode (streaming, polling, offline, one-shot, background) and a Clear button to reset to automatic mode selection.

…ystem

joker23

Only a future consideration comment

joker23 · 2026-03-30T19:06:49Z

    return this._startPromise;
  }

+  setConnectionMode(mode?: FDv2ConnectionMode): void {


For future: setConnectionMode only affects FDv2 so, after we have this out of experimental, we should probably do something to signal that this function is a NOOP when using FDv1

I should probably add a warning now.

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🤖 I have created a release *beep* *boop* --- <details><summary>akamai-edgeworker-sdk-common: 2.0.18</summary> ## [2.0.18](akamai-edgeworker-sdk-common-v2.0.17...akamai-edgeworker-sdk-common-v2.0.18) (2026-04-14) ### Dependencies * The following workspace dependencies were updated * dependencies * @launchdarkly/js-server-sdk-common bumped from ^2.18.3 to ^2.18.4 </details> <details><summary>akamai-server-base-sdk: 3.0.19</summary> ## [3.0.19](akamai-server-base-sdk-v3.0.18...akamai-server-base-sdk-v3.0.19) (2026-04-14) ### Dependencies * The following workspace dependencies were updated * dependencies * @launchdarkly/akamai-edgeworker-sdk-common bumped from ^2.0.17 to ^2.0.18 * @launchdarkly/js-server-sdk-common bumped from ^2.18.3 to ^2.18.4 </details> <details><summary>akamai-server-edgekv-sdk: 1.4.21</summary> ## [1.4.21](akamai-server-edgekv-sdk-v1.4.20...akamai-server-edgekv-sdk-v1.4.21) (2026-04-14) ### Dependencies * The following workspace dependencies were updated * dependencies * @launchdarkly/akamai-edgeworker-sdk-common bumped from ^2.0.17 to ^2.0.18 * @launchdarkly/js-server-sdk-common bumped from ^2.18.3 to ^2.18.4 </details> <details><summary>browser: 0.1.14</summary> ## [0.1.14](browser-v0.1.13...browser-v0.1.14) (2026-04-14) ### Dependencies * The following workspace dependencies were updated * dependencies * @launchdarkly/js-client-sdk bumped from 4.4.1 to 4.5.0 </details> <details><summary>browser-telemetry: 1.0.30</summary> ## [1.0.30](browser-telemetry-v1.0.29...browser-telemetry-v1.0.30) (2026-04-14) ### Dependencies * The following workspace dependencies were updated * devDependencies * @launchdarkly/js-client-sdk bumped from 4.4.1 to 4.5.0 </details> <details><summary>cloudflare-server-sdk: 2.7.18</summary> ## [2.7.18](cloudflare-server-sdk-v2.7.17...cloudflare-server-sdk-v2.7.18) (2026-04-14) ### Dependencies * The following workspace dependencies were updated * dependencies * @launchdarkly/js-server-sdk-common-edge bumped from 2.6.16 to 2.6.17 </details> <details><summary>fastly-server-sdk: 0.2.10</summary> ## [0.2.10](fastly-server-sdk-v0.2.9...fastly-server-sdk-v0.2.10) (2026-04-14) ### Dependencies * The following workspace dependencies were updated * dependencies * @launchdarkly/js-server-sdk-common bumped from 2.18.3 to 2.18.4 </details> <details><summary>jest: 1.0.9</summary> ## [1.0.9](jest-v1.0.8...jest-v1.0.9) (2026-04-14) ### Dependencies * The following workspace dependencies were updated * dependencies * @launchdarkly/react-native-client-sdk bumped from ~10.15.1 to ~10.15.2 </details> <details><summary>js-client-sdk: 4.5.0</summary> ## [4.5.0](js-client-sdk-v4.4.1...js-client-sdk-v4.5.0) (2026-04-14) ### Features * add retry logic to FDv2 polling initializer ([#1230](#1230)) ([fe8bd37](fe8bd37)) * expose setConnectionMode on browser SDK ([#1232](#1232)) ([9019808](9019808)) * FDv2 contract test wiring, suppressions, and example app, cleanup configuration exports. ([#1225](#1225)) ([c67c5f6](c67c5f6)) * wire FDv2 data manager into BrowserClient ([#1222](#1222)) ([0b855f0](0b855f0)) ### Bug Fixes * FDv2 - Support dynamic reconnect URL for streaming. Handle 'error' event types for SSE. ([#1252](#1252)) ([4ef6cdd](4ef6cdd)) ### Dependencies * The following workspace dependencies were updated * dependencies * @launchdarkly/js-client-sdk-common bumped from 1.23.0 to 1.24.0 </details> <details><summary>js-client-sdk-common: 1.24.0</summary> ## [1.24.0](js-client-sdk-common-v1.23.0...js-client-sdk-common-v1.24.0) (2026-04-14) ### Features * add retry logic to FDv2 polling initializer ([#1230](#1230)) ([fe8bd37](fe8bd37)) * expose setConnectionMode on browser SDK ([#1232](#1232)) ([9019808](9019808)) * FDv2 contract test wiring, suppressions, and example app, cleanup configuration exports. ([#1225](#1225)) ([c67c5f6](c67c5f6)) * FDv2DataManagerBase for mode switching and data source lifecycle ([#1210](#1210)) ([8f8051c](8f8051c)) * support per-mode FDv1 fallback configuration ([#1246](#1246)) ([9956bce](9956bce)) * wire FDv2 data manager into BrowserClient ([#1222](#1222)) ([0b855f0](0b855f0)) ### Bug Fixes * FDv2 - Support dynamic reconnect URL for streaming. Handle 'error' event types for SSE. ([#1252](#1252)) ([4ef6cdd](4ef6cdd)) ### Dependencies * The following workspace dependencies were updated * dependencies * @launchdarkly/js-sdk-common bumped from 2.24.0 to 2.24.1 </details> <details><summary>js-sdk-common: 2.24.1</summary> ## [2.24.1](js-sdk-common-v2.24.0...js-sdk-common-v2.24.1) (2026-04-14) ### Bug Fixes * FDv2 - Support dynamic reconnect URL for streaming. Handle 'error' event types for SSE. ([#1252](#1252)) ([4ef6cdd](4ef6cdd)) </details> <details><summary>js-server-sdk-common: 2.18.4</summary> ## [2.18.4](js-server-sdk-common-v2.18.3...js-server-sdk-common-v2.18.4) (2026-04-14) ### Dependencies * The following workspace dependencies were updated * dependencies * @launchdarkly/js-sdk-common bumped from 2.24.0 to 2.24.1 </details> <details><summary>js-server-sdk-common-edge: 2.6.17</summary> ## [2.6.17](js-server-sdk-common-edge-v2.6.16...js-server-sdk-common-edge-v2.6.17) (2026-04-14) ### Dependencies * The following workspace dependencies were updated * dependencies * @launchdarkly/js-server-sdk-common bumped from 2.18.3 to 2.18.4 </details> <details><summary>node-server-sdk: 9.10.11</summary> ## [9.10.11](node-server-sdk-v9.10.10...node-server-sdk-v9.10.11) (2026-04-14) ### Dependencies * The following workspace dependencies were updated * dependencies * @launchdarkly/js-server-sdk-common bumped from 2.18.3 to 2.18.4 </details> <details><summary>node-server-sdk-dynamodb: 6.2.23</summary> ## 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kinyoklion added 5 commits March 30, 2026 11:20

feat: add connection mode buttons to FDv2 example app

3ee2efa

Add a Connection Mode control section with buttons for each FDv2ConnectionMode (streaming, polling, offline, one-shot, background) and a Clear button to reset to automatic mode selection.

fix: lint issues in browser SDK and example app

bcd4888

fix: mark setConnectionMode as @internal with not-ready warning

843688d

fix: add not-ready warning to browser dataSystem config

86b6ae4

kinyoklion force-pushed the rlamb/fdv2-set-connection-mode branch from 21348e5 to 86b6ae4 Compare March 30, 2026 18:20

kinyoklion marked this pull request as ready for review March 30, 2026 18:25

kinyoklion requested a review from a team as a code owner March 30, 2026 18:25

fix: use standard experimental warning on setConnectionMode and dataS…

dd2d6a3

…ystem

joker23 approved these changes Mar 30, 2026

View reviewed changes

fix: warn when setConnectionMode is called without FDv2 data system

adb5c07

cursor Bot reviewed Mar 31, 2026

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Comment thread packages/sdk/browser/src/BrowserClient.ts

fix: validate connection mode before forwarding to data manager

6c98e53

cursor Bot reviewed Mar 31, 2026

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Comment thread packages/sdk/browser/src/BrowserClient.ts Outdated

fix: derive valid connection modes from MODE_TABLE instead of hardcoding

52eafe2

kinyoklion merged commit 9019808 into main Apr 1, 2026
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kinyoklion deleted the rlamb/fdv2-set-connection-mode branch April 1, 2026 17:07

github-actions Bot mentioned this pull request Apr 1, 2026

chore: release main #1221

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feat: expose setConnectionMode on browser SDK#1232

feat: expose setConnectionMode on browser SDK#1232
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