67 lines
2.2 KiB
TypeScript
67 lines
2.2 KiB
TypeScript
/*
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* Copyright 2020 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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interface PerformanceEntryMap {
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'event': PerformanceEventTiming[];
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'first-input': PerformanceEventTiming[];
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'layout-shift': LayoutShift[];
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'largest-contentful-paint': LargestContentfulPaint[];
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'long-animation-frame': PerformanceLongAnimationFrameTiming[];
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'paint': PerformancePaintTiming[];
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'navigation': PerformanceNavigationTiming[];
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'resource': PerformanceResourceTiming[];
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}
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/**
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* Takes a performance entry type and a callback function, and creates a
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* `PerformanceObserver` instance that will observe the specified entry type
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* with buffering enabled and call the callback _for each entry_.
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*
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* This function also feature-detects entry support and wraps the logic in a
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* try/catch to avoid errors in unsupporting browsers.
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*/
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export const observe = <K extends keyof PerformanceEntryMap>(
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type: K,
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callback: (entries: PerformanceEntryMap[K]) => void,
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opts?: PerformanceObserverInit,
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): PerformanceObserver | undefined => {
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try {
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if (PerformanceObserver.supportedEntryTypes.includes(type)) {
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const po = new PerformanceObserver((list) => {
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// Delay by a microtask to workaround a bug in Safari where the
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// callback is invoked immediately, rather than in a separate task.
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// See: https://github.com/GoogleChrome/web-vitals/issues/277
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Promise.resolve().then(() => {
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callback(list.getEntries() as PerformanceEntryMap[K]);
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});
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});
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po.observe(
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Object.assign(
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{
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type,
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buffered: true,
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},
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opts || {},
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) as PerformanceObserverInit,
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);
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return po;
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}
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} catch (e) {
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// Do nothing.
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}
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return;
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};
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