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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 { bindReporter } from './lib/bindReporter.js';
import { getVisibilityWatcher } from './lib/getVisibilityWatcher.js';
import { initMetric } from './lib/initMetric.js';
import { observe } from './lib/observe.js';
import { onBFCacheRestore } from './lib/onBFCacheRestore.js';
import { onHidden } from './lib/onHidden.js';
import { firstInputPolyfill, resetFirstInputPolyfill } from './lib/polyfills/firstInputPolyfill.js';
export const getFID = (onReport, reportAllChanges) => {
const visibilityWatcher = getVisibilityWatcher();
let metric = initMetric('FID');
let report;
const entryHandler = (entry) => {
// Only report if the page wasn't hidden prior to the first input.
if (entry.startTime < visibilityWatcher.firstHiddenTime) {
metric.value = entry.processingStart - entry.startTime;
metric.entries.push(entry);
report(true);
}
};
const po = observe('first-input', entryHandler);
report = bindReporter(onReport, metric, reportAllChanges);
if (po) {
onHidden(() => {
po.takeRecords().map(entryHandler);
po.disconnect();
}, true);
}
if (window.__WEB_VITALS_POLYFILL__) {
// Prefer the native implementation if available,
if (!po) {
window.webVitals.firstInputPolyfill(entryHandler);
}
onBFCacheRestore(() => {
metric = initMetric('FID');
report = bindReporter(onReport, metric, reportAllChanges);
window.webVitals.resetFirstInputPolyfill();
window.webVitals.firstInputPolyfill(entryHandler);
});
}
else {
// Only monitor bfcache restores if the browser supports FID natively.
if (po) {
onBFCacheRestore(() => {
metric = initMetric('FID');
report = bindReporter(onReport, metric, reportAllChanges);
resetFirstInputPolyfill();
firstInputPolyfill(entryHandler);
});
}
}
};