Enhance relative time

src/utils/datetime.ts

@@ -1,33 +1,28 @@
 const relativeTimeFormat = new Intl.RelativeTimeFormat('en', {
   style: 'short',
   numeric: 'auto',
-})
+});
 
-export function getRelativeDateString(date: Date) {
-  const now = new Date()
-  const diff = (date.getTime() - now.getTime()) / 1000
-  let relativeDate
-  if (Math.abs(diff) < 60) {
-    relativeDate = relativeTimeFormat.format(Math.floor(diff), 'second')
-  } else if (Math.abs(diff) < 60 * 60) {
-    relativeDate = relativeTimeFormat.format(Math.floor(diff / 60), 'minute')
-  } else if (Math.abs(diff) < 24 * 60 * 60) {
-    relativeDate = relativeTimeFormat.format(Math.floor(diff / 60 / 60), 'hour')
-  } else if (Math.abs(diff) < 30 * 24 * 60 * 60) {
-    relativeDate = relativeTimeFormat.format(
-      Math.floor(diff / 60 / 60 / 24),
-      'day',
-    )
-  } else if (Math.abs(diff) < 365 * 24 * 60 * 60) {
-    relativeDate = relativeTimeFormat.format(
-      date.getMonth() - now.getMonth(),
-      'month',
-    )
-  } else {
-    relativeDate = relativeTimeFormat.format(
-      date.getFullYear() - now.getFullYear(),
-      'month',
-    )
-  }
-  return relativeDate
-}
+ // Array reprsenting one minute, hour, day, week, month, etc in seconds
+ const cutoffs = [60, 3600, 86400, 86400 * 7, 86400 * 30, 86400 * 365, Infinity];
+
+ // Array equivalent to the above but in the string representation of the units
+ const units: Intl.RelativeTimeFormatUnit[] = ["second", "minute", "hour", "day", "week", "month", "year"];
+
+export function getRelativeDateString(date: Date): string {
+  // Allow dates or times to be passed
+  const timeMs = typeof date === "number" ? date : date.getTime();
+
+  // Get the amount of seconds between the given date and now
+  const deltaSeconds = Math.round((timeMs - Date.now()) / 1000);
+
+  // Grab the ideal cutoff unit
+  const unitIndex = cutoffs.findIndex(cutoff => cutoff > Math.abs(deltaSeconds));
+
+  // Get the divisor to divide from the seconds. E.g. if our unit is "day" our divisor
+  // is one day in seconds, so we can divide our seconds by this to get the # of days
+  const divisor = unitIndex ? cutoffs[unitIndex - 1] : 1;
+
+  // Intl.RelativeTimeFormat do its magic
+  return relativeTimeFormat.format(Math.floor(deltaSeconds / divisor), units[unitIndex]);
+}