ua.js

async function setUAOverride(page, opts = { maskLinux: true }) {
  const browser = page.context().browser();
  const client = await page.context().newCDPSession(page);

  // Determine the full user agent string, strip the "Headless" part
  let ua = opts.userAgent || (await page.evaluate(() => navigator.userAgent)).replace('HeadlessChrome/', 'Chrome/')

  if (opts.maskLinux && ua.includes('Linux') && !ua.includes('Android')) {
    ua = ua.replace(/\(([^)]+)\)/, '(Windows NT 10.0; Win64; x64)') // Replace the first part in parentheses with Windows data
  }

  // Full version number from Chrome
  const uaVersion = ua.includes('Chrome/') ? ua.match(/Chrome\/([\d|.]+)/)[1] : (await browser.version()).match(/\/([\d|.]+)/)[1]

  // Get platform identifier (short or long version)
  const _getPlatform = (extended = false) => {
    if (ua.includes('Mac OS X')) {
      return extended ? 'Mac OS X' : 'MacIntel'
    } else if (ua.includes('Android')) {
      return 'Android'
    } else if (ua.includes('Linux')) {
      return 'Linux'
    } else {
      return extended ? 'Windows' : 'Win32'
    }
  }

  // Source in C++: https://source.chromium.org/chromium/chromium/src/+/master:components/embedder_support/user_agent_utils.cc;l=55-100
  const _getBrands = () => {
    const seed = uaVersion.split('.')[0] // the major version number of Chrome

    const order = [
      [0, 1, 2],
      [0, 2, 1],
      [1, 0, 2],
      [1, 2, 0],
      [2, 0, 1],
      [2, 1, 0]
    ][seed % 6]
    const escapedChars = [' ', ' ', ';']

    const greaseyBrand = `${escapedChars[order[0]]}Not${escapedChars[order[1]]
      }A${escapedChars[order[2]]}Brand`

    const greasedBrandVersionList = []
    greasedBrandVersionList[order[0]] = {
      brand: greaseyBrand,
      version: '99'
    }
    greasedBrandVersionList[order[1]] = {
      brand: 'Chromium',
      version: seed
    }
    greasedBrandVersionList[order[2]] = {
      brand: 'Google Chrome',
      version: seed
    }

    return greasedBrandVersionList
  }

  // Return OS version
  const _getPlatformVersion = () => {
    if (ua.includes('Mac OS X ')) {
      return ua.match(/Mac OS X ([^)]+)/)[1]
    } else if (ua.includes('Android ')) {
      return ua.match(/Android ([^;]+)/)[1]
    } else if (ua.includes('Windows ')) {
      return ua.match(/Windows .*?([\d|.]+);/)[1]
    } else {
      return ''
    }
  }

  // Get architecture, this seems to be empty on mobile and x86 on desktop
  const _getPlatformArch = () => (_getMobile() ? '' : 'x86')

  // Return the Android model, empty on desktop
  const _getPlatformModel = () => _getMobile() ? ua.match(/Android.*?;\s([^)]+)/)[1] : ''

  const _getMobile = () => ua.includes('Android')

  const override = {
    userAgent: ua,
    platform: _getPlatform(),
    userAgentMetadata: {
      brands: _getBrands(),
      fullVersion: uaVersion,
      platform: _getPlatform(true),
      platformVersion: _getPlatformVersion(),
      architecture: _getPlatformArch(),
      model: _getPlatformModel(),
      mobile: _getMobile()
    }
  }

  logger.debug('setUAOverride - Will set these user agent options', {
    override,
    opts: opts
  })

  return client.send('Network.setUserAgentOverride', override)
}