web-vitals
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Easily measure performance metrics in JavaScript
26 lines (25 loc) • 906 B
JavaScript
/*
* 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 bfcacheRestoreTime = -1;
export const getBFCacheRestoreTime = () => bfcacheRestoreTime;
export const onBFCacheRestore = (cb) => {
addEventListener('pageshow', (event) => {
if (event.persisted) {
bfcacheRestoreTime = event.timeStamp;
cb(event);
}
}, true);
};