From d2c6cdb0eca0805136571f7f3e8929e26e374f4a Mon Sep 17 00:00:00 2001
From: Isaac Cambron <icambron@gmail.com>
Date: Sat, 16 Sep 2023 11:25:41 -0400
Subject: [PATCH] use ISO string when converting system zone to JS date

---
 src/datetime.js                 | 9 ++++++++-
 test/datetime/transform.test.js | 6 ++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/datetime.js b/src/datetime.js
index 40c1e6ae1..e0f5673b1 100644
--- a/src/datetime.js
+++ b/src/datetime.js
@@ -47,6 +47,7 @@ import {
   InvalidDateTimeError,
 } from "./errors.js";
 import Invalid from "./impl/invalid.js";
+import SystemZone from "./zones/systemZone.js";
 
 const INVALID = "Invalid DateTime";
 const MAX_DATE = 8.64e15;
@@ -1887,7 +1888,13 @@ export default class DateTime {
    * @return {Date}
    */
   toJSDate() {
-    return new Date(this.isValid ? this.ts : NaN);
+    if (!this.isValid) {
+      return new Date(NaN);
+    } else if (this.zone == SystemZone.instance) {
+      return new Date(this.toISO({ includeOffset: false }));
+    } else {
+      return new Date(this.ts);
+    }
   }
 
   // COMPARE
diff --git a/test/datetime/transform.test.js b/test/datetime/transform.test.js
index 05656c345..cdb49424e 100644
--- a/test/datetime/transform.test.js
+++ b/test/datetime/transform.test.js
@@ -63,6 +63,12 @@ test("DateTime#toJSDate() returns a native Date equivalent", () => {
   expect(js.getTime()).toBe(dt.toMillis());
 });
 
+test("DateTime#toJSDate() works for historic dates with weird offsets", () => {
+  const js = DateTime.fromISO("1800-01-01").toJSDate();
+  expect(js).toBeInstanceOf(Date);
+  expect(js.getFullYear()).toBe(1800);
+});
+
 //------
 // #toBSON()
 //------