npm init -y && npm i puppeteer && node prerender-skyscanner.js

prerender-skyscanner.js

import puppeteer from 'puppeteer';

const browser = await puppeteer.launch({
 executablePath: '/Applications/Google Chrome.app/Contents/MacOS/Google Chrome',
 headless: false,
 args: [
   '--window-size=1818,1328',
   "--no-sandbox",
   "--disable-setuid-sandbox",
   "--disable-dev-shm-usage",
   "--disable-accelerated-2d-canvas",
   "--no-first-run",
   "--no-zygote",
   "--disable-gpu",
   '--deterministic-fetch',
   '--disable-features=IsolateOrigins',
   '--disable-site-isolation-trials',
 ],
 defaultViewport: {
   width: 1818,
   height: 1328,
   deviceScaleFactor: 1,
   isMobile: false,
   hasTouch: false,
   isLandscape: false
 }
})

const page = await browser.newPage()
const TEST_PRERENDER = false

async function delay(milliseconds) {
 return await new Promise(res => setTimeout(() => res(true), milliseconds))
}

await Promise.all([
 page.goto('https://www.skyscanner.net/flights'),
 page.waitForNavigation()
])

await page.click('#acceptCookieButton')

const clickOnFirstLinkCard = async (page) => {
 await page.exposeFunction('delay', delay);
 return await page.evaluate(async (TEST_PRERENDER) => {
   const linkCard = document.querySelector('[data-testid="deal-grid-layout"] a')  
   if (TEST_PRERENDER) {
     const prerenderScript = document.createElement('script')
     prerenderScript.type = 'speculationrules'
     prerenderScript.innerHTML = `{
       "prerender": [
         {
           "urls": ["${linkCard.href}"],
           "eagerness": "eager"
         }
       ]
     }`
     document.body.appendChild(prerenderScript)
   }    
   // add a red circle in the page to mark start of recording and remove after the delay
   const redDotEl = document.createElement('div')
   redDotEl.style.cssText += 'width:30px;height:30px;position:fixed;left:10px;top:10px;z-index:10;background:red;border-radius:50%;'
   document.body.appendChild(redDotEl)
   await delay(2000)
   redDotEl.remove()
   await delay(500)  
   document.getElementsByTagName('html')[0].style.scrollBehavior = 'smooth'
   linkCard.scrollIntoView()
   await delay(1000)
   linkCard.click()
 }, TEST_PRERENDER)
}

await Promise.all([
 clickOnFirstLinkCard(page),
 page.waitForNavigation(),
])

const LCP = await page.evaluate(() => {
 return new Promise(resolve => {
   const getActivationStart = () => {
     const navEntry = window.performance &&
     performance.getEntriesByType &&
     performance.getEntriesByType('navigation')[0]
     return (navEntry && navEntry.activationStart) || 0;
   };

   new PerformanceObserver((entryList) => { 
     const entries = entryList.getEntries()
     const lastEntry = entries[entries.length - 1]
     resolve(
       lastEntry
         ? Math.max(lastEntry.startTime - getActivationStart(), 0)
         : null
     )
   }).observe({ type: 'largest-contentful-paint', buffered: true })
 }) 
})

// https://developer.chrome.com/docs/web-platform/prerender-pages#detecting_prerender_in_javascript
const prerendered = await page.evaluate(() => {
 return (
   document.prerendering ||
   self.performance?.getEntriesByType?.('navigation')[0]?.activationStart > 0
 )
})

console.log('Prerendered:', prerendered)
console.log('LCP:', LCP)

await delay(2000)

await browser.close()

process.exit(0)