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- import { WINDOW } from '../../types.js';
- import { onHidden } from './onHidden.js';
- /*
- * 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.
- */
- let firstHiddenTime = -1;
- const initHiddenTime = () => {
- // If the document is hidden and not prerendering, assume it was always
- // hidden and the page was loaded in the background.
- return WINDOW.document.visibilityState === 'hidden' && !WINDOW.document.prerendering ? 0 : Infinity;
- };
- const trackChanges = () => {
- // Update the time if/when the document becomes hidden.
- onHidden(({ timeStamp }) => {
- firstHiddenTime = timeStamp;
- }, true);
- };
- 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();
- trackChanges();
- }
- return {
- get firstHiddenTime() {
- return firstHiddenTime;
- },
- };
- };
- export { getVisibilityWatcher };
- //# sourceMappingURL=getVisibilityWatcher.js.map
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