From 96ed373da385b4dc66957e965fd243964caaea2b Mon Sep 17 00:00:00 2001
From: Daniel Cassidy <mail@danielcassidy.me.uk>
Date: Fri, 16 Feb 2024 04:13:39 +0000
Subject: [PATCH] feat(latest): normalize Date before returning result

BREAKING CHANGE: The `latest` functions now
throw `Error` if both specified Dates
contain numeric fields that are non-finite.

BREAKING CHANGE: The type parameters of the
`latest` functions have been removed. These
functions now always either return a valid
Date or throw.
---
 index.ts | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/index.ts b/index.ts
index 8c4a9b0..ca71532 100644
--- a/index.ts
+++ b/index.ts
@@ -694,9 +694,14 @@ export const earliestDateFn = earliestFn;
 
 /**
  * Compares two dates and returns the later of the two.
+ *
+ * @throws {Error} if both specified `Date`s contain numeric fields that
+ *   are non-finite.
  */
-export function latest<T extends DateOptions, U extends DateOptions>(a: T, b: U): T | U {
-    return before(a, b) ? b : a;
+export function latest(a: DateOptions, b: DateOptions): Date {
+    const ad = toReferenceDays(a);
+    const bd = toReferenceDays(b);
+    return fromReferenceDays(ad > bd ? ad : bd);
 }
 
 /**
@@ -704,6 +709,9 @@ export function latest<T extends DateOptions, U extends DateOptions>(a: T, b: U)
  *
  * Alias of {@link latest}, useful for disambiguation from similar functions
  * that operate on other date/time types.
+ *
+ * @throws {Error} if both specified `Date`s contain numeric fields that
+ *   are non-finite.
  */
 export const latestDate = latest;
 
@@ -711,8 +719,11 @@ export const latestDate = latest;
  * Compares two dates and returns the later of the two.
  *
  * Curried variant of {@link latest}.
+ *
+ * @throws {Error} if both specified `Date`s contain numeric fields that
+ *   are non-finite.
  */
-export function latestFn<T extends DateOptions, U extends DateOptions>(b: U): (a: T) => T | U {
+export function latestFn(b: DateOptions): (a: DateOptions) => Date {
     return a => latest(a, b);
 }
 
@@ -720,6 +731,9 @@ export function latestFn<T extends DateOptions, U extends DateOptions>(b: U): (a
  * Compares two dates and returns the later of the two.
  *
  * Curried variant of {@link latestDate}.
+ *
+ * @throws {Error} if both specified `Date`s contain numeric fields that
+ *   are non-finite.
  */
 export const latestDateFn = latestFn;