example2.js

const puppeteer = require('puppeteer');
(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto('https://gist.github.com/tmplinshi/b13952a5566ef3b5f05c7e03452002f1');

  await page.waitForSelector('#gist-share-url');
  const element = await page.$('#gist-share-url');

  await element.focus();
  await page.evaluate(e => e.value = '', element);
  // await page.evaluate(e => e.style.background = 'transparent', element);

  await page.evaluate(() => document.body.style.background = 'transparent');
  await element.screenshot({path: 'element.png', omitBackground: true});

  await browser.close();
})();

puppeteer-element-screenshot.js

const puppeteer = require('puppeteer');
(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto('https://google.com');

  await page.waitForSelector('#hplogo');
  const element = await page.$('#hplogo');
  await page.evaluate(() => document.body.style.background = 'transparent');
  await element.screenshot({path: 'google.png', omitBackground: true});
  
  await browser.close();
})();