Apache Flagon UserALE.js makes it easy to capture and customize behavioral telemetry via the runtime JavaScript API (addCallbacks, options, registerExporter). When you need deeper changes, the TypeScript source code under products/userale/packages/flagon-userale/src/ is modular and straightforward to extend.
products/userale/packages/flagon-userale/src/)main.ts: Public module entry point exporting lifecycle functions (start, stop, options, log), callback helpers, and exporters.getInitialSettings.ts: Extracts initial settings from <script data-*> attributes and browser session storage (with SSR safety guards).configure.ts: Singleton Configuration class managing runtime options.attachHandlers.ts: Defines captured DOM/window events, interval buffering, and detail extraction (including automatic masking for <input type="password">).packageLogs.ts: Packages DOM events and custom events into UserALE log objects, executing registered addCallbacks functions.sendLogs.ts: Manages the batch interval timer and pagehide unload flushing, delegating wire serialization and transport to the active LogExporter.exporters/:
types.ts: LogExporter, ExportOptions, ExportResult, and ExporterType interfaces.headers.ts: Unified buildHeaders(config) and chunkLogsForKeepalive (48 KiB chunking for fetch(..., { keepalive: true })).http-json.ts: Default HttpJsonExporter ('http-json' / 'v2-json').otlp-json.ts: Native OpenTelemetry OtlpJsonExporter ('otlp' / 'otlp-json').otel-sdk.ts: OpenTelemetry JS Logs API bridge (OtelSdkExporter).proto-json.ts: Canonical Protobuf v1 JSON exporter (ProtoJsonExporter, 'proto-json').websocket.ts: Persistent WebSocketExporter ('websocket').replay/index.ts: Two-layer Session Replay & Behavioral DOM Telemetry (startSessionReplay, flushSessionReplay, stopSessionReplay, ReplayRingBuffer, RageClickDetector, MutationObserver throttling).After modifying any file in products/userale/packages/flagon-userale/src/, rebuild and run the unit test suite from products/userale:
pnpm build
pnpm --dir packages/flagon-userale test
Contributions are welcome! See our Contributing Guide or open an issue on GitHub.
