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/*
* 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';
import {MetricType} from '../types.js';
export const initMetric = <MetricName extends MetricType['name']>(
name: MetricName,
value?: number,
) => {
const navEntry = getNavigationEntry();
let navigationType: MetricType['navigationType'] = 'navigate';
if (getBFCacheRestoreTime() >= 0) {
navigationType = 'back-forward-cache';
} else if (navEntry) {
if (document.prerendering || getActivationStart() > 0) {
navigationType = 'prerender';
} else if (document.wasDiscarded) {
navigationType = 'restore';
} else if (navEntry.type) {
navigationType = navEntry.type.replace(
/_/g,
'-',
) as MetricType['navigationType'];
}
}
// Use `entries` type specific for the metric.
const entries: Extract<MetricType, {name: MetricName}>['entries'] = [];
return {
name,
value: typeof value === 'undefined' ? -1 : value,
rating: 'good' as const, // If needed, will be updated when reported. `const` to keep the type from widening to `string`.
delta: 0,
entries,
id: generateUniqueID(),
navigationType,
};
};
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