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61 lines
2.6 KiB
61 lines
2.6 KiB
/*
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* Copyright 2022 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import { onTTFB as unattributedOnTTFB } from '../onTTFB.js';
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const attributeTTFB = (metric) => {
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if (metric.entries.length) {
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const navigationEntry = metric.entries[0];
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const activationStart = navigationEntry.activationStart || 0;
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const dnsStart = Math.max(navigationEntry.domainLookupStart - activationStart, 0);
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const connectStart = Math.max(navigationEntry.connectStart - activationStart, 0);
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const requestStart = Math.max(navigationEntry.requestStart - activationStart, 0);
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metric.attribution = {
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waitingTime: dnsStart,
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dnsTime: connectStart - dnsStart,
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connectionTime: requestStart - connectStart,
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requestTime: metric.value - requestStart,
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navigationEntry: navigationEntry,
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};
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return;
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}
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// Set an empty object if no other attribution has been set.
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metric.attribution = {
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waitingTime: 0,
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dnsTime: 0,
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connectionTime: 0,
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requestTime: 0,
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};
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};
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/**
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* Calculates the [TTFB](https://web.dev/time-to-first-byte/) value for the
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* current page and calls the `callback` function once the page has loaded,
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* along with the relevant `navigation` performance entry used to determine the
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* value. The reported value is a `DOMHighResTimeStamp`.
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*
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* Note, this function waits until after the page is loaded to call `callback`
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* in order to ensure all properties of the `navigation` entry are populated.
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* This is useful if you want to report on other metrics exposed by the
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* [Navigation Timing API](https://w3c.github.io/navigation-timing/). For
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* example, the TTFB metric starts from the page's [time
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* origin](https://www.w3.org/TR/hr-time-2/#sec-time-origin), which means it
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* includes time spent on DNS lookup, connection negotiation, network latency,
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* and server processing time.
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*/
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export const onTTFB = (onReport, opts) => {
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unattributedOnTTFB(((metric) => {
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attributeTTFB(metric);
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onReport(metric);
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}), opts);
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};
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