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node_modules/web-vitals/dist/modules/getCLS.js

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+/*
+ * 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 { onBFCacheRestore } from './lib/onBFCacheRestore.js';
+import { bindReporter } from './lib/bindReporter.js';
+export const getCLS = (onReport, reportAllChanges) => {
+    let 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, reportAllChanges);
+        onHidden(() => {
+            po.takeRecords().map(entryHandler);
+            report();
+        });
+        onBFCacheRestore(() => {
+            metric = initMetric('CLS', 0);
+            report = bindReporter(onReport, metric, reportAllChanges);
+        });
+    }
+};