Update app and tooling

node_modules/web-vitals/src/lib/bindReporter.ts

@@ -0,0 +1,48 @@
+/*
+ * 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 {Metric, ReportHandler} from '../types.js';
+
+
+export const bindReporter = (
+  callback: ReportHandler,
+  metric: Metric,
+  po: PerformanceObserver | undefined,
+  observeAllUpdates?: boolean,
+) => {
+  let prevValue: number;
+  return () => {
+    if (po && metric.isFinal) {
+      po.disconnect();
+    }
+    if (metric.value >= 0) {
+      if (observeAllUpdates ||
+          metric.isFinal ||
+          document.visibilityState === 'hidden') {
+        metric.delta = metric.value - (prevValue || 0);
+
+        // Report the metric if there's a non-zero delta, if the metric is
+        // final, or if no previous value exists (which can happen in the case
+        // of the document becoming hidden when the metric value is 0).
+        // See: https://github.com/GoogleChrome/web-vitals/issues/14
+        if (metric.delta || metric.isFinal || prevValue === undefined) {
+          callback(metric);
+          prevValue = metric.value;
+        }
+      }
+    }
+  }
+}