Use Date.toLocaleString instead of an array of month names

src/datetime/timeAgo.ts

@@ -1,51 +1,5 @@
 type Unit = 's' | 'm' | 'h' | 'd';
 
-const shortMonth = (monthIndex: number): string => {
-	const month = [
-		'Jan',
-		'Feb',
-		'Mar',
-		'Apr',
-		'May',
-		'Jun',
-		'Jul',
-		'Aug',
-		'Sep',
-		'Oct',
-		'Nov',
-		'Dec',
-	][monthIndex];
-
-	if (month) {
-		return month;
-	}
-
-	throw new Error(`Invalid month index: ${monthIndex}`);
-};
-
-const longMonth = (monthIndex: number): string => {
-	const month = [
-		'January',
-		'February',
-		'March',
-		'April',
-		'May',
-		'June',
-		'July',
-		'August',
-		'September',
-		'October',
-		'November',
-		'December',
-	][monthIndex];
-
-	if (month) {
-		return month;
-	}
-
-	throw new Error(`Invalid month index: ${monthIndex}`);
-};
-
 const pad = (n: number): number | string => n.toString().padStart(2, '0');
 
 const isWithin24Hours = (date: Date): boolean => {
@@ -151,7 +105,9 @@ export const timeAgo = (
 		// Simple date - "9 Nov 2019"
 		return [
 			then.getDate(),
-			verbose ? longMonth(then.getMonth()) : shortMonth(then.getMonth()),
+			verbose
+				? then.toLocaleString('default', { month: 'long' })
+				: then.toLocaleString('default', { month: 'short' }),
 			then.getFullYear(),
 		].join(' ');
 	}