From 6abd6fde48f7136067f77c70d1c4d64195733f23 Mon Sep 17 00:00:00 2001
From: Ash Searle <ash@hexmen.com>
Date: Fri, 18 Jan 2019 10:16:26 +0000
Subject: [PATCH] Address review comments

---
 src/lib/create/date-from-array.js | 17 +++++++++++------
 src/lib/moment/start-end-of.js    |  6 ++++--
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/lib/create/date-from-array.js b/src/lib/create/date-from-array.js
index 1d577207fe..7fabbc05f1 100644
--- a/src/lib/create/date-from-array.js
+++ b/src/lib/create/date-from-array.js
@@ -1,12 +1,16 @@
 export function createDate (y, m, d, h, M, s, ms) {
-    // the date constructor remaps years 0-99 to 1900-1999
-    var remapYears = (y < 100 && y >= 0);
     // can't just apply() to create a date:
     // https://stackoverflow.com/q/181348
-    var date = new Date(remapYears ? y + 400 : y, m, d, h, M, s, ms);
-
-    if (remapYears && isFinite(date.getFullYear())) {
-        date.setFullYear(y);
+    var date;
+    // the date constructor remaps years 0-99 to 1900-1999
+    if (y < 100 && y >= 0) {
+        // preserve leap years using a full 400 year cycle, then reset
+        date = new Date(y + 400, m, d, h, M, s, ms);
+        if (isFinite(date.getFullYear())) {
+            date.setFullYear(y);
+        }
+    } else {
+        date = new Date(y, m, d, h, M, s, ms);
     }
 
     return date;
@@ -17,6 +21,7 @@ export function createUTCDate (y) {
     // the Date.UTC function remaps years 0-99 to 1900-1999
     if (y < 100 && y >= 0) {
         var args = Array.prototype.slice.call(arguments);
+        // preserve leap years using a full 400 year cycle, then reset
         args[0] = y + 400;
         date = new Date(Date.UTC.apply(null, args));
         if (isFinite(date.getUTCFullYear())) {
diff --git a/src/lib/moment/start-end-of.js b/src/lib/moment/start-end-of.js
index 75942674e4..42c19cbc3b 100644
--- a/src/lib/moment/start-end-of.js
+++ b/src/lib/moment/start-end-of.js
@@ -13,7 +13,8 @@ function mod(dividend, divisor) {
 
 function localStartOfDate(y, m, d) {
     // the date constructor remaps years 0-99 to 1900-1999
-    if (0 <= y && y <= 99) {
+    if (y < 100 && y >= 0) {
+        // preserve leap years using a full 400 year cycle, then reset
         return new Date(y + 400, m, d) - MS_PER_400_YEARS;
     } else {
         return new Date(y, m, d).valueOf();
@@ -22,7 +23,8 @@ function localStartOfDate(y, m, d) {
 
 function utcStartOfDate(y, m, d) {
     // Date.UTC remaps years 0-99 to 1900-1999
-    if (0 <= y && y <= 99) {
+    if (y < 100 && y >= 0) {
+        // preserve leap years using a full 400 year cycle, then reset
         return Date.UTC(y + 400, m, d) - MS_PER_400_YEARS;
     } else {
         return Date.UTC(y, m, d);