You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
61 lines
2.2 KiB
61 lines
2.2 KiB
2 years ago
|
/*
|
||
|
|
* 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 './onBFCacheRestore.js';
|
||
|
|
import { onHidden } from './onHidden.js';
|
||
|
|
let firstHiddenTime = -1;
|
||
|
|
const initHiddenTime = () => {
|
||
|
|
return document.visibilityState === 'hidden' ? 0 : Infinity;
|
||
|
|
};
|
||
|
|
const trackChanges = () => {
|
||
|
|
// Update the time if/when the document becomes hidden.
|
||
|
|
onHidden(({ timeStamp }) => {
|
||
|
|
firstHiddenTime = timeStamp;
|
||
|
|
}, 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.
|
||
|
|
if (window.__WEB_VITALS_POLYFILL__) {
|
||
|
|
firstHiddenTime = window.webVitals.firstHiddenTime;
|
||
|
|
if (firstHiddenTime === Infinity) {
|
||
|
|
trackChanges();
|
||
|
|
}
|
||
|
|
}
|
||
|
|
else {
|
||
|
|
firstHiddenTime = initHiddenTime();
|
||
|
|
trackChanges();
|
||
|
|
}
|
||
|
|
// 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();
|
||
|
|
trackChanges();
|
||
|
|
}, 0);
|
||
|
|
});
|
||
|
|
}
|
||
|
|
return {
|
||
|
|
get firstHiddenTime() {
|
||
|
|
return firstHiddenTime;
|
||
|
|
}
|
||
|
|
};
|
||
|
|
};
|