42 lines
1.5 KiB
JavaScript
42 lines
1.5 KiB
JavaScript
/*
|
|
* 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 { initMetric } from './lib/initMetric.js';
|
|
import { observe } from './lib/observe.js';
|
|
import { onHidden } from './lib/onHidden.js';
|
|
import { bindReporter } from './lib/bindReporter.js';
|
|
export const getCLS = (onReport, reportAllChanges = false) => {
|
|
const metric = initMetric('CLS', 0);
|
|
let report;
|
|
const entryHandler = (entry) => {
|
|
// Only count layout shifts without recent user input.
|
|
if (!entry.hadRecentInput) {
|
|
metric.value += entry.value;
|
|
metric.entries.push(entry);
|
|
report();
|
|
}
|
|
};
|
|
const po = observe('layout-shift', entryHandler);
|
|
if (po) {
|
|
report = bindReporter(onReport, metric, po, reportAllChanges);
|
|
onHidden(({ isUnloading }) => {
|
|
po.takeRecords().map(entryHandler);
|
|
if (isUnloading) {
|
|
metric.isFinal = true;
|
|
}
|
|
report();
|
|
});
|
|
}
|
|
};
|