Network throttling in Puppeteer. Read more: https://fdalvi.github.io/blog/2018-02-05-puppeteer-network-throttle/

list.js

let NETWORK_PRESETS = {
  'GPRS': {
    'offline': false,
    'downloadThroughput': 50 * 1024 / 8,
    'uploadThroughput': 20 * 1024 / 8,
    'latency': 500
  },
  'Regular2G': {
    'offline': false,
    'downloadThroughput': 250 * 1024 / 8,
    'uploadThroughput': 50 * 1024 / 8,
    'latency': 300
  },
  'Good2G': {
    'offline': false,
    'downloadThroughput': 450 * 1024 / 8,
    'uploadThroughput': 150 * 1024 / 8,
    'latency': 150
  },
  'Regular3G': {
    'offline': false,
    'downloadThroughput': 750 * 1024 / 8,
    'uploadThroughput': 250 * 1024 / 8,
    'latency': 100
  },
  'Good3G': {
    'offline': false,
    'downloadThroughput': 1.5 * 1024 * 1024 / 8,
    'uploadThroughput': 750 * 1024 / 8,
    'latency': 40
  },
  'Regular4G': {
    'offline': false,
    'downloadThroughput': 4 * 1024 * 1024 / 8,
    'uploadThroughput': 3 * 1024 * 1024 / 8,
    'latency': 20
  },
  'DSL': {
    'offline': false,
    'downloadThroughput': 2 * 1024 * 1024 / 8,
    'uploadThroughput': 1 * 1024 * 1024 / 8,
    'latency': 5
  },
  'WiFi': {
    'offline': false,
    'downloadThroughput': 30 * 1024 * 1024 / 8,
    'uploadThroughput': 15 * 1024 * 1024 / 8,
    'latency': 2
  }
}

sample.js

const puppeteer = require('puppeteer')

puppeteer.launch().then(async browser => {
  // Create a new tab
  const page = await browser.newPage()

  // Connect to Chrome DevTools
  const client = await page.target().createCDPSession()

  // Set throttling property
  await client.send('Network.emulateNetworkConditions', {
    'offline': false,
    'downloadThroughput': 200 * 1024 / 8,
    'uploadThroughput': 200 * 1024 / 8,
    'latency': 20
  })

  // Navigate and take a screenshot
  await page.goto('https://fdalvi.github.io')
  await page.screenshot({path: 'screenshot.png'})
  await browser.close()
})