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25 lines
1.1 KiB
25 lines
1.1 KiB
/* |
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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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