You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
97 lines
3.3 KiB
97 lines
3.3 KiB
/*
|
|
* 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 {onBFCacheRestore} from './lib/bfcache.js';
|
|
import {bindReporter} from './lib/bindReporter.js';
|
|
import {doubleRAF} from './lib/doubleRAF.js';
|
|
import {getActivationStart} from './lib/getActivationStart.js';
|
|
import {getVisibilityWatcher} from './lib/getVisibilityWatcher.js';
|
|
import {initMetric} from './lib/initMetric.js';
|
|
import {observe} from './lib/observe.js';
|
|
import {whenActivated} from './lib/whenActivated.js';
|
|
import {
|
|
FCPMetric,
|
|
FCPReportCallback,
|
|
MetricRatingThresholds,
|
|
ReportOpts,
|
|
} from './types.js';
|
|
|
|
/** Thresholds for FCP. See https://web.dev/fcp/#what-is-a-good-fcp-score */
|
|
export const FCPThresholds: MetricRatingThresholds = [1800, 3000];
|
|
|
|
/**
|
|
* Calculates the [FCP](https://web.dev/fcp/) value for the current page and
|
|
* calls the `callback` function once the value is ready, along with the
|
|
* relevant `paint` performance entry used to determine the value. The reported
|
|
* value is a `DOMHighResTimeStamp`.
|
|
*/
|
|
export const onFCP = (onReport: FCPReportCallback, opts?: ReportOpts) => {
|
|
// Set defaults
|
|
opts = opts || {};
|
|
|
|
whenActivated(() => {
|
|
const visibilityWatcher = getVisibilityWatcher();
|
|
let metric = initMetric('FCP');
|
|
let report: ReturnType<typeof bindReporter>;
|
|
|
|
const handleEntries = (entries: FCPMetric['entries']) => {
|
|
(entries as PerformancePaintTiming[]).forEach((entry) => {
|
|
if (entry.name === 'first-contentful-paint') {
|
|
po!.disconnect();
|
|
|
|
// Only report if the page wasn't hidden prior to the first paint.
|
|
if (entry.startTime < visibilityWatcher.firstHiddenTime) {
|
|
// The activationStart reference is used because FCP should be
|
|
// relative to page activation rather than navigation start if the
|
|
// page was prerendered. But in cases where `activationStart` occurs
|
|
// after the FCP, this time should be clamped at 0.
|
|
metric.value = Math.max(entry.startTime - getActivationStart(), 0);
|
|
metric.entries.push(entry);
|
|
report(true);
|
|
}
|
|
}
|
|
});
|
|
};
|
|
|
|
const po = observe('paint', handleEntries);
|
|
|
|
if (po) {
|
|
report = bindReporter(
|
|
onReport,
|
|
metric,
|
|
FCPThresholds,
|
|
opts!.reportAllChanges
|
|
);
|
|
|
|
// Only report after a bfcache restore if the `PerformanceObserver`
|
|
// successfully registered or the `paint` entry exists.
|
|
onBFCacheRestore((event) => {
|
|
metric = initMetric('FCP');
|
|
report = bindReporter(
|
|
onReport,
|
|
metric,
|
|
FCPThresholds,
|
|
opts!.reportAllChanges
|
|
);
|
|
|
|
doubleRAF(() => {
|
|
metric.value = performance.now() - event.timeStamp;
|
|
report(true);
|
|
});
|
|
});
|
|
}
|
|
});
|
|
};
|
|
|