Video explanation: https://www.youtube.com/watch?v=rG8cLe7VbW0

index.js

const scraper = require('./scrape.js')
const models = require('./models.js')

const processModels = models => Promise.all(
  models.map(model => processLinks(model, model.urls))
).then(
  result => console.log(JSON.stringify(result))
)

const processLinks = (model, urls) => Promise.all(
  urls.map(url => scraper(model, url))
)

processModels(models)

models.js

module.exports = [

  // Beer Advocate
  {
    domain: 'beeradvocate.com',
    abv: [{type: 'xpath', selector: `//*[@id="info_box"]//b[contains(text(), "ABV")]/following-sibling::text()[1]`}],
    urls: [
      'https://www.beeradvocate.com/beer/profile/35/101/',
    ]
  }

]

sample-output.js

[
  [
    {
      "url": "https://www.beeradvocate.com/beer/profile/35/101/",
      "abv": ["5.60%"]
    }
  ]
]

scrape.js

const puppeteer = require('puppeteer')

module.exports = function(
  model = {},
  url = ''
) {

  return (async () => {

    const browser = await puppeteer.launch()
    const page = await browser.newPage()

    await page.goto(url, {waitUntil: 'networkidle2'})

    const result = await page.evaluate(
      (model, url) => {

        const getValues = selectors => selectors.reduce(
          (acc, selector) => [
            ...acc,
            ...Array.from(
              selector.type === 'css'
              ? document.querySelectorAll(selector.selector)
              : queryXPathAll(selector.selector)
            ).map(
              tag => tag.textContent.replace(/\s(\s+)/g, '').trim()
            ).filter(
              text => text
            )
          ],
          []
        )

        const queryXPathAll = path => {

          const nodes = []
          const xpath = document.evaluate(
            path,
            document,
            null,
            XPathResult.ORDERED_NODE_SNAPSHOT_TYPE,
            null
          )

          for (let i = 0; i < xpath.snapshotLength; i++) {

            nodes.push(xpath.snapshotItem(i))

          }

          return nodes

        }

        const output = {}

        output.url = url

        for (let data in model) {

          if (data !== 'domain' && data !== 'urls') {

            output[data] = getValues(model[data])

          }

        }

        return output

      },
      model,
      url
    )

    await browser.close()

    return result

  })()

}