web-vitals
Version:
Easily measure performance metrics in JavaScript
58 lines • 2.31 kB
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.
*/
import { getBFCacheRestoreTime } from './bfcache.js';
import { generateUniqueID } from './generateUniqueID.js';
import { getActivationStart } from './getActivationStart.js';
import { getNavigationEntry } from './getNavigationEntry.js';
export const initMetric = (name, value = -1, navigationType, navigationId = 0, navigationInteractionId, navigationURL, navigationStartTime) => {
const hardNavEntry = getNavigationEntry();
const hardNavId = hardNavEntry?.navigationId || 0;
let _navigationType = 'navigate';
if (navigationType) {
// If it was passed in, then use that
_navigationType = navigationType;
}
else if (getBFCacheRestoreTime() >= 0) {
_navigationType = 'back-forward-cache';
}
else if (hardNavEntry) {
if (document.prerendering || getActivationStart() > 0) {
_navigationType = 'prerender';
}
else if (document.wasDiscarded) {
_navigationType = 'restore';
}
else if (hardNavEntry.type) {
_navigationType = hardNavEntry.type.replace(/_/g, '-');
}
}
// Use `entries` type specific for the metric.
const entries = [];
return {
name,
value,
rating: 'good', // If needed, will be updated when reported. `const` to keep the type from widening to `string`.
delta: 0,
entries,
id: generateUniqueID(),
navigationType: _navigationType,
navigationId: navigationId || hardNavId,
navigationInteractionId: navigationInteractionId,
navigationURL: navigationURL || hardNavEntry?.name,
navigationStartTime: navigationStartTime || 0,
};
};
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