diff options
| author | altaf-creator <dev@altafcreator.com> | 2025-11-09 11:15:19 +0800 |
|---|---|---|
| committer | altaf-creator <dev@altafcreator.com> | 2025-11-09 11:15:19 +0800 |
| commit | 8eff962cab608341a6f2fedc640a0e32d96f26e2 (patch) | |
| tree | 05534d1a720ddc3691d346c69b4972555820a061 /frontend-old/node_modules/web-vitals/dist/modules/onFCP.js | |
pain
Diffstat (limited to 'frontend-old/node_modules/web-vitals/dist/modules/onFCP.js')
| -rw-r--r-- | frontend-old/node_modules/web-vitals/dist/modules/onFCP.js | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/frontend-old/node_modules/web-vitals/dist/modules/onFCP.js b/frontend-old/node_modules/web-vitals/dist/modules/onFCP.js new file mode 100644 index 0000000..f4350cf --- /dev/null +++ b/frontend-old/node_modules/web-vitals/dist/modules/onFCP.js @@ -0,0 +1,71 @@ +/* + * 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'; +/** Thresholds for FCP. See https://web.dev/articles/fcp#what_is_a_good_fcp_score */ +export const FCPThresholds = [1800, 3000]; +/** + * Calculates the [FCP](https://web.dev/articles/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, opts) => { + // Set defaults + opts = opts || {}; + whenActivated(() => { + const visibilityWatcher = getVisibilityWatcher(); + let metric = initMetric('FCP'); + let report; + const handleEntries = (entries) => { + entries.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); + }); + }); + } + }); +}; |
