Selenium Webdriver Node.js take screenshots of entire page

webdriver_full_page_screenshots.js

var webdriver = require('selenium-webdriver')
var assert = require('assert')
var fs = require('fs')

// Input capabilities
var capabilities = {
 'browserName' : 'Chrome',
 'browser_version' : '66.0',
 'os' : 'Windows',
 'os_version' : '10',
 'resolution' : '1024x768',
 'browserstack.user' : 'abc',
 'browserstack.key' : '123'
}

var driver = new webdriver.Builder().
usingServer('http://hub-cloud.browserstack.com/wd/hub').
withCapabilities(capabilities).
build()

webdriver.WebDriver.prototype.saveScreenshot = filename => {
  return driver.takeScreenshot().then(data =>  {
    fs.writeFile(`${__dirname}/screenshots/${filename}`, data.replace(/^data:image\/png;base64,/,''), 'base64', err => {
      if(err) throw err
    })
  })
}

async function main() {
  var now = (Date.now()/1e3)|0
  await driver.get('https://example.com')
  var title = await driver.getTitle()
  assert(title, 'Some title')

  var totalHeight = await driver.executeScript('return document.body.offsetHeight')
  var windowHeight = await driver.executeScript('return window.outerHeight')

  for (var i = 0; i <= (totalHeight/windowHeight); i++) {
    await driver.executeScript(`window.scrollTo(0, window.outerHeight*${i})`)
    driver.saveScreenshot(`home-${i}-${now}.png`)
  }

  driver.quit()
  console.log('done')
}

main()

I think this code doesn't make one fullpage screenshot. It just makes several screenshots that of the whole page. Do you have a solution for just one picture of the whole page?