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34 lines
1.3 KiB
34 lines
1.3 KiB
2 years ago
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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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export const bindReporter = (callback, metric, reportAllChanges) => {
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let prevValue;
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return (forceReport) => {
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if (metric.value >= 0) {
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if (forceReport || reportAllChanges) {
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metric.delta = metric.value - (prevValue || 0);
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// Report the metric if there's a non-zero delta or if no previous
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// value exists (which can happen in the case of the document becoming
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// hidden when the metric value is 0).
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// See: https://github.com/GoogleChrome/web-vitals/issues/14
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if (metric.delta || prevValue === undefined) {
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prevValue = metric.value;
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callback(metric);
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}
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}
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}
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};
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};
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