An Introduction to Puppeteer: Automating with Headless Chrome

Headless browsers have become increasingly popular in recent years for various tasks, such as web scraping, automated testing, creating screenshots, and generating PDFs. These browsers run without a graphical user interface (GUI), enabling developers to automate and control them using a command-line interface or programming language.

One of the most widely used libraries for controlling headless browsers is Puppeteer, a Node.js library that offers a high-level API for controlling Chrome/Chromium via the Dev Tools Protocol. By default, Puppeteer operates in headless mode, which does not display a graphical user interface (GUI) for the browser. However, one of the library’s benefits is that it can also be configured to run in non-headless (head-full) Chrome/Chromium, which can aid in debugging.

In this article, we will dive into the capabilities of Puppeteer and its ability to automate and control headless Chrome/Chromium. We will cover installing Puppeteer and interacting with its API.

Installing Puppeteer Library

The initial step in setting up Puppeteer is installing it in your development environment. Puppeteer can be installed using npm, the package manager for Node.js. Before installing Puppeteer, ensure that you have Node.js and npm installed on your system. With Node.js and npm properly set up, you can use the following command to install Puppeteer:

npm install puppeteer

Alternatively, you can also install the puppeteer via yarn

yarn add puppeteer

Basic Overview of the API

Once you have Puppeteer installed, you can start using its API to control Chrome/Chromium. The Puppeteer API is designed to be simple and intuitive to use and provides many powerful features, such as:

puppeteer.launch(): Launches a browser instance

browser.newPage(): Creates a new tab/page in the browser

page.goto(): Navigate the page to a given URL

page.$eval(): Runs a function in the context of the page

page.screenshot(): Takes a screenshot of the page

Here is an example of a “Hello, World!” program using Puppeteer:

const puppeteer = require('puppeteer');

(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto('https://example.com');
  console.log(await page.title());
  await browser.close();
})(); 

In this example, we first import the Puppeteer library using the require function. Then, we use an async function to launch a browser instance using puppeteer.launch(). Next, we create a new page using browser.newPage() and navigate to the URL “https://example.com” using page.goto(). Then, we use console.log(await page.title()) to log the title of the page to the console. Finally, we close the browser using browser.close().

“Hello, World!” example can be more improved using try-catch block when working with Puppeteer to handle and properly log errors. This will help you to identify and fix issues in your code, and to prevent your script from crashing

Here’s an example of how you can use try-catch with Puppeteer

try {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto('https://example.com');
  console.log(await page.title());
} catch (error) {
  console.error(error);
} finally {
  await browser.close();
}

Async/await used in the example code because Puppeteer uses JavaScript Promises to handle the flow of control in its API. JavaScript Promises are used to handle asynchronous operations, such as loading a web page or taking a screenshot. async/await is a more modern and simpler way to handle Promises, making the code more readable and easier to understand.