added orai

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

@@ -0,0 +1,79 @@
+/*
+ * 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 { initMetric } from './lib/initMetric.js';
+import { onBFCacheRestore } from './lib/bfcache.js';
+import { getNavigationEntry } from './lib/getNavigationEntry.js';
+import { getActivationStart } from './lib/getActivationStart.js';
+import { whenActivated } from './lib/whenActivated.js';
+/** Thresholds for TTFB. See https://web.dev/articles/ttfb#what_is_a_good_ttfb_score */
+export const TTFBThresholds = [800, 1800];
+/**
+ * Runs in the next task after the page is done loading and/or prerendering.
+ * @param callback
+ */
+const whenReady = (callback) => {
+    if (document.prerendering) {
+        whenActivated(() => whenReady(callback));
+    }
+    else if (document.readyState !== 'complete') {
+        addEventListener('load', () => whenReady(callback), true);
+    }
+    else {
+        // Queue a task so the callback runs after `loadEventEnd`.
+        setTimeout(callback, 0);
+    }
+};
+/**
+ * Calculates the [TTFB](https://web.dev/articles/ttfb) value for the
+ * current page and calls the `callback` function once the page has loaded,
+ * along with the relevant `navigation` performance entry used to determine the
+ * value. The reported value is a `DOMHighResTimeStamp`.
+ *
+ * Note, this function waits until after the page is loaded to call `callback`
+ * in order to ensure all properties of the `navigation` entry are populated.
+ * This is useful if you want to report on other metrics exposed by the
+ * [Navigation Timing API](https://w3c.github.io/navigation-timing/). For
+ * example, the TTFB metric starts from the page's [time
+ * origin](https://www.w3.org/TR/hr-time-2/#sec-time-origin), which means it
+ * includes time spent on DNS lookup, connection negotiation, network latency,
+ * and server processing time.
+ */
+export const onTTFB = (onReport, opts) => {
+    // Set defaults
+    opts = opts || {};
+    let metric = initMetric('TTFB');
+    let report = bindReporter(onReport, metric, TTFBThresholds, opts.reportAllChanges);
+    whenReady(() => {
+        const navigationEntry = getNavigationEntry();
+        if (navigationEntry) {
+            // The activationStart reference is used because TTFB should be
+            // relative to page activation rather than navigation start if the
+            // page was prerendered. But in cases where `activationStart` occurs
+            // after the first byte is received, this time should be clamped at 0.
+            metric.value = Math.max(navigationEntry.responseStart - getActivationStart(), 0);
+            metric.entries = [navigationEntry];
+            report(true);
+            // Only report TTFB after bfcache restores if a `navigation` entry
+            // was reported for the initial load.
+            onBFCacheRestore(() => {
+                metric = initMetric('TTFB', 0);
+                report = bindReporter(onReport, metric, TTFBThresholds, opts.reportAllChanges);
+                report(true);
+            });
+        }
+    });
+};