1 files changed, 134 insertions, 0 deletions
diff --git a/frontend-old/node_modules/web-vitals/src/onLCP.ts b/frontend-old/node_modules/web-vitals/src/onLCP.ts
new file mode 100644
index 0000000..57f0a85
--- /dev/null
+++ b/frontend-old/node_modules/web-vitals/src/onLCP.ts
@@ -0,0 +1,134 @@
+/*
+ * 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 {onBFCacheRestore} from './lib/bfcache.js';
+import {bindReporter} from './lib/bindReporter.js';
+import {doubleRAF} from './lib/doubleRAF.js';
+import {getActivationStart} from './lib/getActivationStart.js';
+import {getVisibilityWatcher} from './lib/getVisibilityWatcher.js';
+import {initMetric} from './lib/initMetric.js';
+import {observe} from './lib/observe.js';
+import {onHidden} from './lib/onHidden.js';
+import {runOnce} from './lib/runOnce.js';
+import {whenActivated} from './lib/whenActivated.js';
+import {whenIdle} from './lib/whenIdle.js';
+import {LCPMetric, MetricRatingThresholds, ReportOpts} from './types.js';
+
+/** Thresholds for LCP. See https://web.dev/articles/lcp#what_is_a_good_lcp_score */
+export const LCPThresholds: MetricRatingThresholds = [2500, 4000];
+
+const reportedMetricIDs: Record<string, boolean> = {};
+
+/**
+ * Calculates the [LCP](https://web.dev/articles/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`.
+ *
+ * If the `reportAllChanges` configuration option is set to `true`, the
+ * `callback` function will be called any time a new `largest-contentful-paint`
+ * performance entry is dispatched, or once the final value of the metric has
+ * been determined.
+ */
+export const onLCP = (
+  onReport: (metric: LCPMetric) => void,
+  opts?: ReportOpts,
+) => {
+  // Set defaults
+  opts = opts || {};
+
+  whenActivated(() => {
+    const visibilityWatcher = getVisibilityWatcher();
+    let metric = initMetric('LCP');
+    let report: ReturnType<typeof bindReporter>;
+
+    const handleEntries = (entries: LCPMetric['entries']) => {
+      // If reportAllChanges is set then call this function for each entry,
+      // otherwise only consider the last one.
+      if (!opts!.reportAllChanges) {
+        entries = entries.slice(-1);
+      }
+
+      entries.forEach((entry) => {
+        // Only report if the page wasn't hidden prior to LCP.
+        if (entry.startTime < visibilityWatcher.firstHiddenTime) {
+          // 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. But in cases
+          // where `activationStart` occurs after the LCP, this time should be
+          // clamped at 0.
+          metric.value = Math.max(entry.startTime - getActivationStart(), 0);
+          metric.entries = [entry];
+          report();
+        }
+      });
+    };
+
+    const po = observe('largest-contentful-paint', handleEntries);
+
+    if (po) {
+      report = bindReporter(
+        onReport,
+        metric,
+        LCPThresholds,
+        opts!.reportAllChanges,
+      );
+
+      const stopListening = runOnce(() => {
+        if (!reportedMetricIDs[metric.id]) {
+          handleEntries(po!.takeRecords() as LCPMetric['entries']);
+          po!.disconnect();
+          reportedMetricIDs[metric.id] = true;
+          report(true);
+        }
+      });
+
+      // Stop listening after input. Note: while scrolling is an input that
+      // stops LCP observation, it's unreliable since it can be programmatically
+      // generated. See: https://github.com/GoogleChrome/web-vitals/issues/75
+      ['keydown', 'click'].forEach((type) => {
+        // Wrap in a setTimeout so the callback is run in a separate task
+        // to avoid extending the keyboard/click handler to reduce INP impact
+        // https://github.com/GoogleChrome/web-vitals/issues/383
+        addEventListener(type, () => whenIdle(stopListening), {
+          once: true,
+          capture: true,
+        });
+      });
+
+      onHidden(stopListening);
+
+      // Only report after a bfcache restore if the `PerformanceObserver`
+      // successfully registered.
+      onBFCacheRestore((event) => {
+        metric = initMetric('LCP');
+        report = bindReporter(
+          onReport,
+          metric,
+          LCPThresholds,
+          opts!.reportAllChanges,
+        );
+
+        doubleRAF(() => {
+          metric.value = performance.now() - event.timeStamp;
+          reportedMetricIDs[metric.id] = true;
+          report(true);
+        });
+      });
+    }
+  });
+};