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26 lines
1.1 KiB
26 lines
1.1 KiB
2 years ago
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/*
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* Copyright 2020 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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let firstHiddenTime = document.visibilityState === 'hidden' ? 0 : Infinity;
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const onVisibilityChange = (event) => {
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if (document.visibilityState === 'hidden') {
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firstHiddenTime = event.timeStamp;
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removeEventListener('visibilitychange', onVisibilityChange, true);
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}
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};
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// Note: do not add event listeners unconditionally (outside of polyfills).
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addEventListener('visibilitychange', onVisibilityChange, true);
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export const getFirstHiddenTime = () => firstHiddenTime;
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