refactor: add types

Author: John Doe

packages/utils/src/lib/performance-observer.ts

@@ -24,9 +24,10 @@ export class PerformanceObserverSink<T>
   #flushThreshold: number;
   #sink: Sink<T, unknown>;
   #observer: PerformanceObserver | undefined;
-  #observedTypes: EntryType[] = ['mark', 'measure'];
-  #getEntries = (list: PerformanceObserverEntryList) =>
-    this.#observedTypes.flatMap(t => list.getEntriesByType(t));
+  readonly #observedTypes: EntryType[] = ['mark', 'measure'];
+  #getEntries = (list: {
+    getEntriesByType: (t: EntryType) => PerformanceEntry[];
+  }) => this.#observedTypes.flatMap(t => list.getEntriesByType(t));
   #observedCount: number = 0;
 
   constructor(options: PerformanceObserverOptions<T>) {

packages/utils/src/perf-hooks.d.ts

@@ -40,6 +40,10 @@ declare module 'node:perf_hooks' {
     duration?: number;
   }
 
+  export interface PerformanceObserverEntryList {
+    getEntriesByType: (type: EntryType) => PerformanceEntry[];
+  }
+
   const performance: {
     mark: (name: string, options?: PerformanceMarkOptions) => PerformanceMark;
 
@@ -48,5 +52,7 @@ declare module 'node:perf_hooks' {
       startOrOptions?: string | number | PerformanceMeasureOptions,
       end?: string | number,
     ) => PerformanceMeasure;
+
+    getEntriesByType: (type: EntryType) => PerformanceEntry[];
   };
 }