file.js

module.exports = async () => {
        const page = await browser.newPage()
        await page.goto('https://www.example.com', {
          waitUntil: 'networkidle'
        })

        // const html = await page.content()
        const buffer = await page.screenshot()

        await page.close()

        return {
          image: buffer.toString('base64')
          // html
        }
      }