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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Returns a promise that is resolved when the specified number of animation
// frames has occurred.
async function waitUntilAfterNextLayout() {
let frameCount = 2;
return new Promise(resolve => {
const handleFrame = () => {
if (--frameCount <= 0)
resolve();
else
requestAnimationFrame(handleFrame);
};
requestAnimationFrame(handleFrame);
});
};
async function observeUntilNumEntries(n, opts) {
return new Promise((resolve) => {
const entries = [];
const observer = new PerformanceObserver((list) => {
for (const entry of list.getEntries()) {
entries.push(entry);
}
if (entries.length >= n) {
observer.disconnect();
resolve(entries);
}
});
observer.observe(opts);
});
}
async function waitForNumLayoutShiftEntries(num) {
let entries = await observeUntilNumEntries(num, {
type: 'layout-shift',
buffered: true,
});
return entries.map((entry) => ({
startTime: entry.startTime,
score: entry.value,
hadRecentInput: entry.hadRecentInput,
}));
}
const getLcp = async (resource) => {
return await new Promise(resolve => {
const observer = new PerformanceObserver((list) => {
const entries = list.getEntries().filter(e => e.url.includes(resource));
if (entries.length > 0) {
resolve(entries[entries.length - 1].startTime)
}
});
observer.observe({ type: "largest-contentful-paint", buffered: true });
})
}
const getRequestStart = (name) =>
getResourceTimingEntry(name).requestStart;
const getResponseEnd = (name) =>
getResourceTimingEntry(name).responseEnd;
const getStartTime = (name) =>
getResourceTimingEntry(name).startTime;
const getResourceTimingEntry = (name) => {
return performance.getEntriesByType('resource').filter(
e => e.name.includes(name))[0];
}
const addImageWithUrl = async (url) => {
await new Promise(resolve => {
const img = document.createElement('img');
img.addEventListener('load', resolve);
img.src = url;
document.body.appendChild(img);
});
}
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