Can Puppetteer Check Css

CSS Programming

As a web developer, one of the crucial aspects of testing and automating browser interactions is the ability to check CSS properties and styles. In my experience, I have found Puppeteer to be an excellent tool for this purpose. Puppeteer is a Node.js library that provides a high-level API for controlling headless Chrome or Chromium browsers. It allows you to automate tasks such as generating screenshots, scraping web content, and even simulating user interactions. But can Puppeteer check CSS? Let’s dive deeper into this topic and find out.

Before we proceed, let’s clarify what CSS is and why it plays a vital role in web development. CSS, short for Cascading Style Sheets, is a style sheet language used to describe the presentation of a document written in HTML. It defines how elements should be rendered on a web page, including layout, colors, fonts, and more. As a developer, having the ability to verify and manipulate CSS properties is essential for ensuring the accuracy and consistency of a web application’s appearance.

Now, coming back to Puppeteer, the answer is a definite yes – Puppeteer can indeed check CSS properties and styles. Puppeteer provides a powerful set of APIs that allow you to interact with the DOM (Document Object Model) of a web page. By using these APIs, you can access and manipulate the CSS properties of any element on the page.

Let’s take a look at an example. Suppose we have a web page with a button element that has a CSS class of “btn-primary” and a background color of blue defined in its CSS. We can use Puppeteer to check if the background color is indeed blue:

const puppeteer = require('puppeteer');

(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();

await page.goto('');

const buttonBackgroundColor = await page.$eval('.btn-primary', el => {
return window.getComputedStyle(el).getPropertyValue('background-color');

if (buttonBackgroundColor === 'rgb(0, 0, 255)') {
console.log('The button background color is blue.');
} else {
console.log('The button background color is not blue.');

await browser.close();

In this example, Puppeteer is used to launch a headless browser, navigate to a web page, and check the background color of a button element with the class “btn-primary”. The page.$eval() method is utilized to evaluate a function in the context of the browser DOM and return the value of the CSS property ‘background-color’ for the specified element. By comparing the returned value with the expected color, we can determine whether the button background color is blue or not.

Puppeteer also provides other methods for accessing and manipulating CSS properties, such as page.$$eval() for evaluating functions on multiple elements, page.waitForSelector() for waiting until a specific CSS selector is present, and page.evaluate() for executing JavaScript code within the page’s context.


In conclusion, Puppeteer is a powerful tool for automating browser interactions and can indeed check CSS properties and styles. With Puppeteer, you can access and manipulate CSS properties of any element on a web page, allowing you to verify and ensure the accuracy of the website’s appearance. This capability is crucial for web developers in testing and automating their applications. So, if you are looking to automate browser testing and CSS checking, Puppeteer is definitely worth considering.