[Perf] Use cache for getFirstLetters

src/util/dateFormat.ts

@@ -1,4 +1,5 @@
 import { LangFn } from '../hooks/useLang';
+import withCache from './withCache';
 
 const WEEKDAYS_FULL = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
 const MONTHS_FULL = [
@@ -246,18 +247,8 @@ export function formatVoiceRecordDuration(durationInMs: number) {
   return `${parts.join(':')},${String(milliseconds).padStart(2, '0')}`;
 }
 
-// `toLocaleString` is slow so we use cache
-const dateFormatCache = new Map<string, string>();
-
-export function formatDateToString(datetime: Date | number, locale = 'en-US') {
-  const date = typeof datetime === 'number' ? new Date(datetime) : datetime;
-  const cacheKey = `${locale}_${getDayStartAt(date)}`;
-  const cached = dateFormatCache.get(cacheKey);
-  if (cached) {
-    return cached;
-  }
-
-  const newValue = date.toLocaleString(
+const formatDayToStringWithCache = withCache((dayStartAt: number, locale: string) => {
+  return new Date(dayStartAt).toLocaleString(
     locale,
     {
       year: 'numeric',
@@ -265,10 +256,13 @@ export function formatDateToString(datetime: Date | number, locale = 'en-US') {
       day: 'numeric',
     },
   );
+});
 
-  dateFormatCache.set(cacheKey, newValue);
+export function formatDateToString(datetime: Date | number, locale = 'en-US') {
+  const date = typeof datetime === 'number' ? new Date(datetime) : datetime;
+  const dayStartAt = getDayStartAt(date);
 
-  return newValue;
+  return formatDayToStringWithCache(dayStartAt, locale);
 }
 
 export function formatDateTimeToString(datetime: Date | number, locale = 'en-US') {

src/util/textFormat.ts

@@ -1,5 +1,6 @@
 import EMOJI_REGEX from '../lib/twemojiRegex';
 import { fixNonStandardEmoji } from './emoji';
+import withCache from './withCache';
 
 export function formatInteger(value: number) {
   return String(value).replace(/\d(?=(\d{3})+$)/g, '$& ');
@@ -26,7 +27,7 @@ export function formatIntegerCompact(views: number) {
   return `${formatFixedNumber(views / 1e6)}M`;
 }
 
-export function getFirstLetters(phrase: string, count = 2) {
+export const getFirstLetters = withCache((phrase: string, count = 2) => {
   return phrase
     .replace(/[.,!@#$%^&*()_+=\-`~[\]/\\{}:"|<>?]+/gi, '')
     .trim()
@@ -42,4 +43,4 @@ export function getFirstLetters(phrase: string, count = 2) {
       return word.match(/./u)![0].toUpperCase();
     })
     .join('');
-}
+});

src/util/withCache.ts

@@ -0,0 +1,24 @@
+const cache = new WeakMap<AnyFunction, Map<string, any>>();
+
+export default function withCache<T extends AnyFunction>(fn: T) {
+  return (...args: Parameters<T>): ReturnType<T> => {
+    let fnCache = cache.get(fn);
+    const cacheKey = args.map(String).join('_');
+
+    if (fnCache) {
+      const cached = fnCache.get(cacheKey);
+      if (cached) {
+        return cached;
+      }
+    } else {
+      fnCache = new Map();
+      cache.set(fn, fnCache);
+    }
+
+    const newValue = fn(...args);
+
+    fnCache.set(cacheKey, newValue);
+
+    return newValue;
+  };
+}