v3.8.1: feat() add type guard and type for ws orderbook events

src/util/index.ts

@@ -1,5 +1,6 @@
 export * from './BaseRestClient';
-export * from './requestUtils';
-export * from './WsStore';
 export * from './logger';
+export * from './requestUtils';
+export * from './typeGuards';
 export * from './websocket-util';
+export * from './WsStore';

src/util/typeGuards.ts

@@ -0,0 +1,29 @@
+/**
+ * Use type guards to narrow down types with minimal efforts.
+ */
+
+import { WSOrderbookEventV5 } from '../types/websocket.events';
+
+/**
+ * Type guard to detect a V5 orderbook event (delta & snapshots)
+ *
+ * @param event
+ * @returns
+ */
+export function isWsOrderbookEventV5(
+  event: unknown,
+): event is WSOrderbookEventV5 {
+  if (
+    typeof event !== 'object' ||
+    !event ||
+    typeof event['topic'] !== 'string' ||
+    typeof event['type'] !== 'string'
+  ) {
+    return false;
+  }
+
+  return (
+    ['delta', 'snapshot'].includes(event['type']) &&
+    event['topic'].startsWith('orderbook')
+  );
+}