31 lines
1.2 KiB
JavaScript
31 lines
1.2 KiB
JavaScript
/*
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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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export const onHidden = (cb, once) => {
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const onHiddenOrPageHide = (event) => {
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if (event.type === 'pagehide' || document.visibilityState === 'hidden') {
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cb(event);
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if (once) {
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removeEventListener('visibilitychange', onHiddenOrPageHide, true);
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removeEventListener('pagehide', onHiddenOrPageHide, true);
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}
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}
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};
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addEventListener('visibilitychange', onHiddenOrPageHide, true);
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// Some browsers have buggy implementations of visibilitychange,
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// so we use pagehide in addition, just to be safe.
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addEventListener('pagehide', onHiddenOrPageHide, true);
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};
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