launchdarkly-node-client-sdk

import { initialize, LDContext, LDClient } from 'launchdarkly-node-client-sdk'; const clientSideId = process.env.LAUNCHDARKLY_CLIENT_SIDE_ID ?? 'YOUR_CLIENT_SIDE_ID_HERE'; if (clientSideId === 'YOUR_CLIENT_SIDE_ID_HERE') { console.warn('Please set the LAUNCHDARKLY_CLIENT_SIDE_ID environment variable or replace the placeholder.'); } async function runFeatureFlagExample() { const context: LDContext = { kind: 'user', key: 'example-user-key', name: 'Example User', // You can add custom attributes here, e.g.: // country: 'us', // anonymous: true, }; console.log('Initializing LaunchDarkly client...'); const client: LDClient = initialize(clientSideId, context); try { // Wait for the client to connect to LaunchDarkly. A timeout is highly recommended. // e.g., await client.waitForInitialization(5000); await client.waitForInitialization(); console.log('LaunchDarkly client initialized.'); // Evaluate a feature flag const showNewFeature = client.variation('new-feature', false); // 'new-feature' is flag key, false is default value console.log(`Feature flag 'new-feature' is ${showNewFeature ? 'ON' : 'OFF'}.`); const welcomeMessage = client.variation('welcome-message', 'Hello, user!'); console.log(`Welcome message: "${welcomeMessage}"`); // You can also track custom events client.track('button-click', context, { buttonId: 'primary-cta' }); console.log('Custom event "button-click" tracked.'); } catch (error) { console.error('Failed to initialize LaunchDarkly client or evaluate flags:', error); } finally { // Always close the client when done to ensure all events are sent and connections are closed console.log('Closing LaunchDarkly client...'); client.close(); console.log('Client closed.'); } } runFeatureFlagExample();