init

node_modules/@sentry-internal/tracing/cjs/browser/web-vitals/getLCP.js

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+Object.defineProperty(exports, '__esModule', { value: true });
+
+const types = require('../types.js');
+const bindReporter = require('./lib/bindReporter.js');
+const getActivationStart = require('./lib/getActivationStart.js');
+const getVisibilityWatcher = require('./lib/getVisibilityWatcher.js');
+const initMetric = require('./lib/initMetric.js');
+const observe = require('./lib/observe.js');
+const onHidden = require('./lib/onHidden.js');
+
+/*
+ * 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.
+ */
+
+const reportedMetricIDs = {};
+
+/**
+ * Calculates the [LCP](https://web.dev/lcp/) value for the current page and
+ * calls the `callback` function once the value is ready (along with the
+ * relevant `largest-contentful-paint` performance entry used to determine the
+ * value). The reported value is a `DOMHighResTimeStamp`.
+ */
+const onLCP = (onReport) => {
+  const visibilityWatcher = getVisibilityWatcher.getVisibilityWatcher();
+  const metric = initMetric.initMetric('LCP');
+  let report;
+
+  const handleEntries = (entries) => {
+    const lastEntry = entries[entries.length - 1] ;
+    if (lastEntry) {
+      // The startTime attribute returns the value of the renderTime if it is
+      // not 0, and the value of the loadTime otherwise. The activationStart
+      // reference is used because LCP should be relative to page activation
+      // rather than navigation start if the page was prerendered.
+      const value = Math.max(lastEntry.startTime - getActivationStart.getActivationStart(), 0);
+
+      // Only report if the page wasn't hidden prior to LCP.
+      if (value < visibilityWatcher.firstHiddenTime) {
+        metric.value = value;
+        metric.entries = [lastEntry];
+        report();
+      }
+    }
+  };
+
+  const po = observe.observe('largest-contentful-paint', handleEntries);
+
+  if (po) {
+    report = bindReporter.bindReporter(onReport, metric);
+
+    const stopListening = () => {
+      if (!reportedMetricIDs[metric.id]) {
+        handleEntries(po.takeRecords() );
+        po.disconnect();
+        reportedMetricIDs[metric.id] = true;
+        report(true);
+      }
+    };
+
+    // Stop listening after input. Note: while scrolling is an input that
+    // stop LCP observation, it's unreliable since it can be programmatically
+    // generated. See: https://github.com/GoogleChrome/web-vitals/issues/75
+    ['keydown', 'click'].forEach(type => {
+      if (types.WINDOW.document) {
+        addEventListener(type, stopListening, { once: true, capture: true });
+      }
+    });
+
+    onHidden.onHidden(stopListening, true);
+
+    return stopListening;
+  }
+
+  return;
+};
+
+exports.onLCP = onLCP;
+//# sourceMappingURL=getLCP.js.map