Update app and tooling

node_modules/web-vitals/src/getLCP.ts

@@ -0,0 +1,65 @@
+/*
+ * 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 {bindReporter} from './lib/bindReporter.js';
+import {getFirstHidden} from './lib/getFirstHidden.js';
+import {initMetric} from './lib/initMetric.js';
+import {observe, PerformanceEntryHandler} from './lib/observe.js';
+import {onHidden} from './lib/onHidden.js';
+import {whenInput} from './lib/whenInput.js';
+import {ReportHandler} from './types.js';
+
+
+export const getLCP = (onReport: ReportHandler, reportAllChanges = false) => {
+  const metric = initMetric('LCP');
+  const firstHidden = getFirstHidden();
+
+  let report: ReturnType<typeof bindReporter>;
+
+  const entryHandler = (entry: PerformanceEntry) => {
+    // The startTime attribute returns the value of the renderTime if it is not 0,
+    // and the value of the loadTime otherwise.
+    const value = entry.startTime;
+
+    // If the page was hidden prior to paint time of the entry,
+    // ignore it and mark the metric as final, otherwise add the entry.
+    if (value < firstHidden.timeStamp) {
+      metric.value = value;
+      metric.entries.push(entry);
+    } else {
+      metric.isFinal = true;
+    }
+
+    report();
+  };
+
+  const po = observe('largest-contentful-paint', entryHandler);
+
+  if (po) {
+    report = bindReporter(onReport, metric, po, reportAllChanges);
+
+    const onFinal = () => {
+      if (!metric.isFinal) {
+        po.takeRecords().map(entryHandler as PerformanceEntryHandler);
+        metric.isFinal = true;
+        report();
+      }
+    }
+
+    whenInput().then(onFinal);
+    onHidden(onFinal, true);
+  }
+};