42 lines
1.5 KiB
JavaScript
42 lines
1.5 KiB
JavaScript
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/*
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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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/**
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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 = (type, callback) => {
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try {
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if (PerformanceObserver.supportedEntryTypes.includes(type)) {
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// More extensive feature detect needed for Firefox due to:
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// https://github.com/GoogleChrome/web-vitals/issues/142
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if (type === 'first-input' && !('PerformanceEventTiming' in self)) {
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return;
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}
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const po = new PerformanceObserver((l) => l.getEntries().map(callback));
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po.observe({ type, buffered: true });
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return po;
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}
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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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