npm init -y && npm i puppeteer && node index.js

index.js

import puppeteer from 'puppeteer';

const browser = await puppeteer.launch({
  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 = true

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

await Promise.all([
  page.goto(`https://www.farfetch.com/${TEST_PRERENDER ? 'fr' : 'uk'}/sets/most-wanted-pieces.aspx`),
  page.waitForNavigation()
])

async function getProductCardCoordinates(page) {
  return await page.evaluate(() => {
    const productCardClientRects = document
      .querySelector('li[data-testid="productCard"]:nth-child(1) a[data-component="ProductCardLink"]')
      .getClientRects()[0]
  
    return {
      left: productCardClientRects.left,
      top: productCardClientRects.top
    }
  })
}

async function hoverOverProductLinks(page) {
  const productCardClientRects = await getProductCardCoordinates(page)
  var x = Number(productCardClientRects.left + 10, 10)
  var y = Number(productCardClientRects.top + 750, 10)
  
  for (var i = 0; i <= 4; i++) {
    await page.mouse.move(x, y, {steps: 200})
    x += 300
    await delay(1000)
  }
}

async function getPrerenderedPathFromPage(page) {
  if (!TEST_PRERENDER) {
    return '/uk/shopping/men/amiri-stars-court-low-sneakers-item-22775645.aspx?storeid=9446'
  }

  const speculationRule = await page.evaluate(() => {
    const speculationRules = document.querySelectorAll('script[type=speculationrules]')
    if (!speculationRules?.length) return null
    return JSON.parse(speculationRules?.[3]?.innerText || '')
  })
  return speculationRule ? speculationRule.prerender?.[0]?.urls?.[0] : null
}

await hoverOverProductLinks(page)
await delay(4000)
await hoverOverProductLinks(page)
await delay(4000)

const prerenderedPath = await getPrerenderedPathFromPage(page)
if (!prerenderedPath) {
  console.log('❌ No prerendered page was found')
  await browser.close()
  process.exit(0)
}
await delay(4000)

await Promise.all([
  page.click(`a[href='${prerenderedPath}']`),
  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()