export event comparator.

core.test.ts

@@ -1,5 +1,21 @@
 import { test, expect } from 'bun:test'
-import { sortEvents } from './core.ts'
+import { compareEvents, sortEvents } from './core.ts'
+
+test('compareEvents', () => {
+  const event = {
+    id: 'abc123',
+    pubkey: 'key1',
+    created_at: 1620000000,
+    kind: 1,
+    tags: [],
+    content: 'Hello',
+    sig: 'sig1',
+  }
+
+  expect(compareEvents(event, { ...event, created_at: 1610000000 })).toBeLessThan(0)
+  expect(compareEvents(event, { ...event, id: 'abc124' })).toBeLessThan(0)
+  expect(compareEvents(event, { ...event })).toBe(0)
+})
 
 test('sortEvents', () => {
   const events = [

core.ts

@@ -52,16 +52,22 @@ export function validateEvent<T>(event: T): event is T & UnsignedEvent {
   return true
 }
 
+/**
+ * Compare events in reverse-chronological order by the `created_at` timestamp,
+ * and then by the event `id` (lexicographically) in case of ties.
+ */
+export function compareEvents(a: Event, b: Event): number {
+  if (a.created_at !== b.created_at) {
+    return b.created_at - a.created_at
+  }
+  return a.id.localeCompare(b.id)
+}
+
 /**
  * Sort events in reverse-chronological order by the `created_at` timestamp,
  * and then by the event `id` (lexicographically) in case of ties.
  * This mutates the array.
  */
 export function sortEvents(events: Event[]): Event[] {
-  return events.sort((a: NostrEvent, b: NostrEvent): number => {
+  return events.sort(compareEvents)
-    if (a.created_at !== b.created_at) {
-      return b.created_at - a.created_at
-    }
-    return a.id.localeCompare(b.id)
-  })
 }