We call the action of extracting data from web pages web scraping. Scraping is useful for a variety of use cases:

1. In testing and monitoring, asserting against the state of one or more elements on a page
2. In general, gathering data for a variety of different purposes

Scraping element attributes & properties

Below is an example running against our test site (opens new window), getting and printing out the href attribute of the first a element on the homepage. That just happens to be our logo, which links right back to our homepage, and therefore will have an href value equal to the URL we navigate to using page.goto():

const puppeteer = require("puppeteer");

(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto("https://danube-webshop.herokuapp.com");
  const url = await page.$eval("a", (el) => el.href);
  console.log(url);
  await browser.close();
})();

const { chromium } = require("playwright");

(async () => {
  const browser = await chromium.launch();
  const page = await browser.newPage();
  await page.goto("https://danube-webshop.herokuapp.com");
  const url = await page.$eval("a", (el) => el.href);
  console.log(url);
  await browser.close();
})();

As an alternative, it is also possible to retrieve an ElementHandle (opens new window) and then retrieve a property value from it. Following is an example printing the href value of the first a element of our homepage:

const puppeteer = require("puppeteer");

(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto("https://danube-webshop.herokuapp.com");
  const element = await page.$("a");
  const href = await element.evaluate((node) => node.href);
  console.log(href);
  await browser.close();
})();

const { chromium } = require("playwright");

(async () => {
  const browser = await chromium.launch();
  const page = await browser.newPage();
  await page.goto("https://danube-webshop.herokuapp.com");
  const element = await page.$("a");
  const href = await element.evaluate((node) => node.href);
  console.log(href);
  await browser.close();
})();

TIP

The innerText property is often used in tests to assert that some element on the page contains the expected text.

Scraping lists of elements

Scraping element lists is just as easy. For example, let's grab the innerText of each product category shown on the homepage:

const puppeteer = require("puppeteer");

(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto("https://danube-webshop.herokuapp.com");
  const categories = await page.$$eval("li a", (nodes) =>
    nodes.map((n) => n.innerText)
  );
  console.log(categories);
  await browser.close();
})();

const { chromium } = require("playwright");

(async () => {
  const browser = await chromium.launch();
  const page = await browser.newPage();
  await page.goto("https://danube-webshop.herokuapp.com");
  const categories = await page.$$eval("li a", (nodes) =>
    nodes.map((n) => n.innerText)
  );
  console.log(categories);
  await browser.close();
})();

Scraping images

Scraping images from a page is also possible. For example, we can easily get the logo of our test website and save it as a file:

const puppeteer = require("puppeteer");
const axios = require("axios");
const fs = require("fs");

(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto("https://danube-webshop.herokuapp.com");
  const url = await page.$eval("img", (el) => el.src);

  const response = await axios.get(url);
  fs.writeFileSync("scraped-image.svg", response.data);

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

const { chromium } = require("playwright");
const axios = require("axios");
const fs = require("fs");

(async () => {
  const browser = await chromium.launch();
  const page = await browser.newPage();
  await page.goto("https://danube-webshop.herokuapp.com");
  const url = await page.$eval("img", (el) => el.src);

  const response = await axios.get(url);
  fs.writeFileSync("scraped-image.svg", response.data);

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

We are using axios (opens new window) to make a GET request against the source URL of the image. The response body will contain the image itself, which can be written to a file using fs (opens new window).

Generating JSON from scraping

Once we start scraping more information, we might want to have it stored in a standard format for later use. Let's gather the title, author and price from each book that appears on the home page of our test site:

The code for that could look like this:

const puppeteer = require("puppeteer");
const fs = require("fs");

(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto("https://danube-webshop.herokuapp.com");
  const content = await page.evaluate(() => {
    let data = [];

    let books = document.querySelectorAll(".preview");
    books.forEach((book) => {
      let title = book.querySelector(".preview-title").innerText;
      let author = book.querySelector(".preview-author").innerText;
      let price = book.querySelector(".preview-price").innerText;
      data.push({
        title,
        author,
        price,
      });
    });
    return data;
  });

  const jsonData = JSON.stringify(content);
  fs.writeFileSync("books.json", jsonData);
  await browser.close();
})();

const { chromium } = require("playwright");
const fs = require("fs");

(async () => {
  const browser = await chromium.launch();
  const page = await browser.newPage();
  await page.goto("https://danube-webshop.herokuapp.com");
  const content = await page.evaluate(() => {
    let data = [];

    let books = document.querySelectorAll(".preview");
    books.forEach((book) => {
      let title = book.querySelector(".preview-title").innerText;
      let author = book.querySelector(".preview-author").innerText;
      let price = book.querySelector(".preview-price").innerText;
      data.push({
        title,
        author,
        price,
      });
    });
    return data;
  });

  const jsonData = JSON.stringify(content);
  fs.writeFileSync("books.json", jsonData);
  await browser.close();
})();

The resulting books.json file will look like the following:

[
  { "title": "Haben oder haben",
    "author": "Fric Eromm",
    "price": "$9.95"
  },
  {
    "title": "Parry Hotter",
    "author": "J/K Rowlin'",
    "price": "$9.95"
  },
  {
    "title": "Laughterhouse-Five",
    "author": "Truk Tugennov",
    "price": "$9.95"
  },
  {
    "title": "To Mock a Killingbird",
    "author": "Larper Hee",
    "price": "$9.95"
  },
  ...
]

All the above examples can be run as follows:

node scraping.js

node scraping.js

Further reading

1. Puppeteer (opens new window)'s and Playwright (opens new window)'s official API reference on the topic
2. An E2E example test asserting agains an element's innerText
3. An excellent introduction to scraping with Puppeteer (opens new window) by Nick Chikovani
4. A practical tutorial on web scraping with Puppeteer (opens new window) by Kartik Singh