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const loader = new loadScript();
loader.load([
    '//apis.google.com/js/client:platform.js?onload=startApp',
    '//cdnjs.cloudflare.com/ajax/libs/dropbox.js/0.10.3/dropbox.min.js'
]).then(({length}) => {
    console.log(`${length} scripts loaded!`);
});

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[lcp]
const po = new PerformanceObserver(() => {});
po.observe({type: 'largest-contentful-paint', buffered: true});
const lastEntry = po.takeRecords().slice(-1)[0];
return lastEntry.renderTime || lastEntry.loadTime;

[cls]
const po = new PerformanceObserver(() => {});
po.observe({type: 'layout-shift', buffered: true});
return po.takeRecords().reduce((val, entry) => val + entry.value, 0);

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const puppeteer = require('puppeteer');
const devices = require('puppeteer/DeviceDescriptors');

const Good3G = {
    'offline': false,
    'downloadThroughput': 1.5 * 1024 * 1024 / 8,
    'uploadThroughput': 750 * 1024 / 8,
    'latency': 40
};

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git log --pretty=format:"* %s" v0.0.8..v0.1.0 > changelog.md

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<img data-src="unicorn.jpg" loading="lazy" alt=".." class="lazyload"/>

<script>
// Select all images with the class "lazyload"
const images = document.querySelectorAll("img.lazyload");
// Check if the browser supports the "loading" attribute
if ('loading' in HTMLImageElement.prototype) {
  // If so, we'll update all <img src> to point to the data-src instead
  images.forEach(img => {
    img.src = img.dataset.src;

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• Web Page Usability Matters
• PageSpeed Insights w/Lighthouse and Chrome User Experience Report
• Data Saver for Chrome on Android - enable and then look at about:flags for Lite Pages and other interventions
• web.dev/fast - code-labs and tooling for optimizing performance
• Lighthousebot for using Lighthouse in continuous integration
• Bundlesize for JavaScript budgets in CI
• Start performance budgeting

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• part 1
• part 2
• part 3
• part 4

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// Examples at https://gist.github.com/bendc/9b05735dfa6966859025#gistcomment-1370485


// array utils
// =================================================================================================

const combine = (...arrays) => [].concat(...arrays);

const compact = arr => arr.filter(Boolean);

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Working with a React codebase and want to use Preact? Ideally, you should use preact and preact-compat for your dev, prod and test builds. This will enable you to discover any interop bugs early on. If you would prefer to only alias preact and preact-compat in Webpack for production builds (e.g if your preference is using React DevTools and enzyme), make sure to thoroughly test everything works as expected before deploying to your servers.

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Workbox runtime caching recipes

Your Service Worker script will need to import in Workbox and initialize it before calling any of the routes documented in this write-up, similar to the below:

importScripts('workbox-sw.prod.v1.3.0.js');
const workbox = new WorkboxSW();

// Placeholder array populated automatically by workboxBuild.injectManifest()