feat: Serialize Temporal.Instant

Author: razor-x

package-lock.json

@@ -68,6 +68,7 @@
     "npm": ">= 9.0.0"
   },
   "devDependencies": {
+    "@js-temporal/polyfill": "^0.4.4",
     "@types/node": "^20.8.10",
     "ava": "^6.0.1",
     "axios": "^1.6.5",

package.json

@@ -13,3 +13,20 @@ export const isDateLike = (v: unknown): v is DateLike => {
   }
   return false
 }
+
+interface TemporalInstantLike {
+  epochMilliseconds: number
+}
+
+export const isTemporalInstantLike = (v: unknown): v is TemporalInstantLike => {
+  if (v == null) return false
+  if (typeof v !== 'object') return false
+  if (!('epochMilliseconds' in v)) return false
+  try {
+    if (typeof v.epochMilliseconds !== 'number') return false
+    if (isNaN(v.epochMilliseconds)) return false
+    return true
+  } catch {
+    return false
+  }
+}

src/lib/date.ts

@@ -1,4 +1,4 @@
-import { isDateLike } from './date.js'
+import { isDateLike, isTemporalInstantLike } from './date.js'
 
 type Params = Record<string, unknown>
 
@@ -41,6 +41,9 @@ const serialize = (k: string, v: unknown): string => {
   if (typeof v === 'bigint') return v.toString()
   if (typeof v === 'boolean') return v.toString()
   if (isDateLike(v)) return v.toISOString()
+  if (isTemporalInstantLike(v)) {
+    return new Date(v.epochMilliseconds).toISOString()
+  }
   throw new UnserializableParamError(k, `is a ${typeof v}`)
 }
 

src/lib/serialize.ts

@@ -1,3 +1,4 @@
+import { Temporal } from '@js-temporal/polyfill'
 import test from 'ava'
 
 import {
@@ -82,6 +83,17 @@ test('serializes Date', (t) => {
   )
 })
 
+test.only('serializes Temporal.Instant', (t) => {
+  t.is(
+    serializeUrlSearchParams({
+      foo: 1,
+      now: Temporal.Instant.fromEpochMilliseconds(1740422679000),
+    }),
+
+    'foo=1&now=2025-02-24T18%3A44%3A39.000Z',
+  )
+})
+
 test('cannot serialize unserializable values', (t) => {
   t.throws(() => serializeUrlSearchParams({ foo: {} }), {
     instanceOf: UnserializableParamError,