diff options
Diffstat (limited to 'frontend-old/node_modules/web-vitals/dist/modules/onLCP.js')
| -rw-r--r-- | frontend-old/node_modules/web-vitals/dist/modules/onLCP.js | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/frontend-old/node_modules/web-vitals/dist/modules/onLCP.js b/frontend-old/node_modules/web-vitals/dist/modules/onLCP.js new file mode 100644 index 0000000..2f9d0f7 --- /dev/null +++ b/frontend-old/node_modules/web-vitals/dist/modules/onLCP.js @@ -0,0 +1,106 @@ +/* + * 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 { onHidden } from './lib/onHidden.js'; +import { runOnce } from './lib/runOnce.js'; +import { whenActivated } from './lib/whenActivated.js'; +import { whenIdle } from './lib/whenIdle.js'; +/** Thresholds for LCP. See https://web.dev/articles/lcp#what_is_a_good_lcp_score */ +export const LCPThresholds = [2500, 4000]; +const reportedMetricIDs = {}; +/** + * Calculates the [LCP](https://web.dev/articles/lcp) value for the current page and + * calls the `callback` function once the value is ready (along with the + * relevant `largest-contentful-paint` performance entry used to determine the + * value). The reported value is a `DOMHighResTimeStamp`. + * + * If the `reportAllChanges` configuration option is set to `true`, the + * `callback` function will be called any time a new `largest-contentful-paint` + * performance entry is dispatched, or once the final value of the metric has + * been determined. + */ +export const onLCP = (onReport, opts) => { + // Set defaults + opts = opts || {}; + whenActivated(() => { + const visibilityWatcher = getVisibilityWatcher(); + let metric = initMetric('LCP'); + let report; + const handleEntries = (entries) => { + // If reportAllChanges is set then call this function for each entry, + // otherwise only consider the last one. + if (!opts.reportAllChanges) { + entries = entries.slice(-1); + } + entries.forEach((entry) => { + // Only report if the page wasn't hidden prior to LCP. + if (entry.startTime < visibilityWatcher.firstHiddenTime) { + // The startTime attribute returns the value of the renderTime if it is + // not 0, and the value of the loadTime otherwise. The activationStart + // reference is used because LCP should be relative to page activation + // rather than navigation start if the page was prerendered. But in cases + // where `activationStart` occurs after the LCP, this time should be + // clamped at 0. + metric.value = Math.max(entry.startTime - getActivationStart(), 0); + metric.entries = [entry]; + report(); + } + }); + }; + const po = observe('largest-contentful-paint', handleEntries); + if (po) { + report = bindReporter(onReport, metric, LCPThresholds, opts.reportAllChanges); + const stopListening = runOnce(() => { + if (!reportedMetricIDs[metric.id]) { + handleEntries(po.takeRecords()); + po.disconnect(); + reportedMetricIDs[metric.id] = true; + report(true); + } + }); + // Stop listening after input. Note: while scrolling is an input that + // stops LCP observation, it's unreliable since it can be programmatically + // generated. See: https://github.com/GoogleChrome/web-vitals/issues/75 + ['keydown', 'click'].forEach((type) => { + // Wrap in a setTimeout so the callback is run in a separate task + // to avoid extending the keyboard/click handler to reduce INP impact + // https://github.com/GoogleChrome/web-vitals/issues/383 + addEventListener(type, () => whenIdle(stopListening), { + once: true, + capture: true, + }); + }); + onHidden(stopListening); + // Only report after a bfcache restore if the `PerformanceObserver` + // successfully registered. + onBFCacheRestore((event) => { + metric = initMetric('LCP'); + report = bindReporter(onReport, metric, LCPThresholds, opts.reportAllChanges); + doubleRAF(() => { + metric.value = performance.now() - event.timeStamp; + reportedMetricIDs[metric.id] = true; + report(true); + }); + }); + } + }); +}; |
