web-vitals
Version:
Easily measure performance metrics in JavaScript
43 lines (42 loc) • 1.58 kB
JavaScript
/*
* Copyright 2022 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.
*/
const getNavigationEntryFromPerformanceTiming = () => {
const timing = performance.timing;
const type = performance.navigation.type;
const navigationEntry = {
entryType: 'navigation',
startTime: 0,
type: type == 2 ? 'back_forward' : (type === 1 ? 'reload' : 'navigate'),
};
for (const key in timing) {
if (key !== 'navigationStart' && key !== 'toJSON') {
navigationEntry[key] = Math.max(timing[key] -
timing.navigationStart, 0);
}
}
return navigationEntry;
};
export const getNavigationEntry = () => {
if (window.__WEB_VITALS_POLYFILL__) {
return window.performance && (performance.getEntriesByType &&
performance.getEntriesByType('navigation')[0] ||
getNavigationEntryFromPerformanceTiming());
}
else {
return window.performance && (performance.getEntriesByType &&
performance.getEntriesByType('navigation')[0]);
}
};