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authoraltaf-creator <dev@altafcreator.com>2025-11-16 19:08:29 +0800
committeraltaf-creator <dev@altafcreator.com>2025-11-16 19:08:29 +0800
commit434aa8343fdcbb4d5002f934979913c099489bee (patch)
tree55bab4ec5a6151be57797d34f61faf5ea744471b /frontend-old/node_modules/web-vitals/src/lib/getVisibilityWatcher.ts
parent893c388d4e99442a36005e5971a87730623f946e (diff)
sdk, del
Diffstat (limited to 'frontend-old/node_modules/web-vitals/src/lib/getVisibilityWatcher.ts')
-rw-r--r--frontend-old/node_modules/web-vitals/src/lib/getVisibilityWatcher.ts89
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diff --git a/frontend-old/node_modules/web-vitals/src/lib/getVisibilityWatcher.ts b/frontend-old/node_modules/web-vitals/src/lib/getVisibilityWatcher.ts
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--- a/frontend-old/node_modules/web-vitals/src/lib/getVisibilityWatcher.ts
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-/*
- * Copyright 2020 Google LLC
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import {onBFCacheRestore} from './bfcache.js';
-
-let firstHiddenTime = -1;
-
-const initHiddenTime = () => {
- // If the document is hidden when this code runs, assume it was always
- // hidden and the page was loaded in the background, with the one exception
- // that visibility state is always 'hidden' during prerendering, so we have
- // to ignore that case until prerendering finishes (see: `prerenderingchange`
- // event logic below).
- return document.visibilityState === 'hidden' && !document.prerendering
- ? 0
- : Infinity;
-};
-
-const onVisibilityUpdate = (event: Event) => {
- // If the document is 'hidden' and no previous hidden timestamp has been
- // set, update it based on the current event data.
- if (document.visibilityState === 'hidden' && firstHiddenTime > -1) {
- // If the event is a 'visibilitychange' event, it means the page was
- // visible prior to this change, so the event timestamp is the first
- // hidden time.
- // However, if the event is not a 'visibilitychange' event, then it must
- // be a 'prerenderingchange' event, and the fact that the document is
- // still 'hidden' from the above check means the tab was activated
- // in a background state and so has always been hidden.
- firstHiddenTime = event.type === 'visibilitychange' ? event.timeStamp : 0;
-
- // Remove all listeners now that a `firstHiddenTime` value has been set.
- removeChangeListeners();
- }
-};
-
-const addChangeListeners = () => {
- addEventListener('visibilitychange', onVisibilityUpdate, true);
- // IMPORTANT: when a page is prerendering, its `visibilityState` is
- // 'hidden', so in order to account for cases where this module checks for
- // visibility during prerendering, an additional check after prerendering
- // completes is also required.
- addEventListener('prerenderingchange', onVisibilityUpdate, true);
-};
-
-const removeChangeListeners = () => {
- removeEventListener('visibilitychange', onVisibilityUpdate, true);
- removeEventListener('prerenderingchange', onVisibilityUpdate, true);
-};
-
-export const getVisibilityWatcher = () => {
- if (firstHiddenTime < 0) {
- // If the document is hidden when this code runs, assume it was hidden
- // since navigation start. This isn't a perfect heuristic, but it's the
- // best we can do until an API is available to support querying past
- // visibilityState.
- firstHiddenTime = initHiddenTime();
- addChangeListeners();
-
- // Reset the time on bfcache restores.
- onBFCacheRestore(() => {
- // Schedule a task in order to track the `visibilityState` once it's
- // had an opportunity to change to visible in all browsers.
- // https://bugs.chromium.org/p/chromium/issues/detail?id=1133363
- setTimeout(() => {
- firstHiddenTime = initHiddenTime();
- addChangeListeners();
- }, 0);
- });
- }
- return {
- get firstHiddenTime() {
- return firstHiddenTime;
- },
- };
-};