added orai

24_12_09/node_modules/web-vitals/dist/modules/onLCP.js

@@ -0,0 +1,106 @@
+/*
+ * 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';
+/** Thresholds for LCP. See https://web.dev/articles/lcp#what_is_a_good_lcp_score */
+export const LCPThresholds = [2500, 4000];
+const reportedMetricIDs = {};
+/**
+ * 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, opts) => {
+    // Set defaults
+    opts = opts || {};
+    whenActivated(() => {
+        const visibilityWatcher = getVisibilityWatcher();
+        let metric = initMetric('LCP');
+        let report;
+        const handleEntries = (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());
+                    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);
+                });
+            });
+        }
+    });
+};