feat: cache date/time descriptor (#124)

.github/CODEOWNERS

@@ -0,0 +1 @@
+* @BrightspaceUI/gaudi-dev

lib/common.js

@@ -88,6 +88,7 @@ export function validateFormatValue(value) {
 class DocumentLocaleSettings {
 
  constructor() {
+ this._cache = new Map();
  this._htmlElem = window.document.getElementsByTagName('html')[0];
  this._listeners = [];
  this._overrides = {};
@@ -101,6 +102,7 @@ class DocumentLocaleSettings {
  set fallbackLanguage(val) {
  const normalized = this._normalize(val);
  if (normalized === this._fallbackLanguage) return;
+ this._cache.clear();
  this._fallbackLanguage = normalized;
  this._listeners.forEach((cb) => cb());
  }
@@ -109,6 +111,7 @@ class DocumentLocaleSettings {
  set language(val) {
  const normalized = this._normalize(val);
  if (normalized === this._language) return;
+ this._cache.clear();
  this._language = normalized;
  this._listeners.forEach((cb) => cb());
  }
@@ -123,6 +126,7 @@ class DocumentLocaleSettings {
  delete val.date.formats.timeFormats;
  }
  }
+ this._cache.clear();
  this._overrides = val;
  this._listeners.forEach((cb) => cb());
  }
@@ -131,13 +135,21 @@ class DocumentLocaleSettings {
  this._listeners.push(cb);
  }
 
+ getCacheItem(key, provider) {
+ if (!this._cache.has(key)) {
+ this._cache.set(key, provider());
+ }
+ return this._cache.get(key);
+ }
+
  removeChangeListener(cb) {
  const index = this._listeners.indexOf(cb);
  if (index < 0) return;
  this._listeners.splice(index, 1);
  }
 
  reset() {
+ this._cache.clear();
  this._language = this._languageInitial;
  this._fallbackLanguage = null;
  this.overrides = {};