SSR 側のタイムゾーン調整

Author: kkeisuke

utils/functions/index.ts

@@ -1,17 +1,33 @@
+const TIME_ZONE = 9
+
 export const formatDateTime = (dateString: string): string => {
-  const date = new Date(dateString)
-  // Invalid Date
-  if (Number.isNaN(date.getTime())) {
+  const date = getDate(dateString)
+  if (isInvalidDate(date)) {
     return dateString
   }
   return new Intl.DateTimeFormat('ja', { year: 'numeric', month: '2-digit', day: '2-digit', hour: '2-digit', minute: '2-digit' }).format(date)
 }
 
 export const formatDateTimeForInput = (dateString: string): string => {
-  const date = new Date(dateString)
-  // Invalid Date
-  if (Number.isNaN(date.getTime())) {
+  const date = getDate(dateString)
+  if (isInvalidDate(date)) {
     return dateString
   }
-  return new Date(date.getTime() - date.getTimezoneOffset() * 60 * 1000).toISOString().slice(0, 16)
+  return toISOStringWithTimezone(date).slice(0, 16)
+}
+
+function getDate(dateString: string) {
+  const date = new Date(dateString)
+  if (date.getTimezoneOffset() === 0) {
+    date.setHours(date.getHours() + TIME_ZONE)
+  }
+  return date
+}
+
+function isInvalidDate(date: Date) {
+  return Number.isNaN(date.getTime())
+}
+
+function toISOStringWithTimezone(date: Date) {
+  return new Date(date.getTime() - date.getTimezoneOffset() * 60 * 1000).toISOString()
 }