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Browser DevTools

Learn about browser DevTools and how you can use them to collect data from a website.

Even though DevTools stands for developer tools, everyone can use them to inspect a website. Each major browser has their own DevTools. We will use Chrome DevTools as an example, but the advice is applicable to any browser, as the tools are extremely similar. To open Chrome DevTools, press F12 or right-click anywhere in the page and choose Inspect.

Elements tab

When you first open Chrome DevTools, you will start on the Elements tab (In Firefox it's called the Inspector). You can use the tab to inspect the page's HTML on the left and also its CSS on the right. The items in the HTML view are called elements and they are all enclosed in HTML tags. For example <div>, <p>, and <span> are tags. When you add something inside of those tags, like <p>Hello!</p> you create an element. You can also see elements inside elements in the Elements tab. This is called nesting and it gives the page its structure.

At the bottom there's the JavaScript console which you can use to manipulate the website. If the Console is not there, you can press ESC to toggle it. At first it looks super complicated, but don't worry, there's no need to understand everything.

Chrome DevTools with elements tab and console

Selecting an element

In the top left corner of the DevTools, there's a little arrow icon. When you click it and then hover your mouse over the website's content, DevTools will show you information about the HTML elements. And when you click, the element will be selected in the Elements tab.

Chrome DevTools element selection hover effect

Interacting with an element

After you select an element, you can right-click the highlighted element in the Elements tab to show a menu with available actions. For now, select Store as global variable (Use in Console in Firefox). You'll see that a new variable called temp1 (temp0 in Firefox) appeared in your DevTools Console. You can now use the console to access the element's properties using JavaScript.

For example, if you wanted to scrape the text in the element, you could use the textContent property to get it. The following command will get the text of your temp1 element and print it to the console using the console.log() function.


You can also get the HTML of the element using this command:


And you could even change the text of the element, if you wanted to:

temp1.textContent = 'Hello!';

Chrome DevTools JavaScript command execution

You can interact with the page in many more ways using the Console. If you want to dive deeper we recommend this tutorial on documents. A web page in a browser is called a document.

Next up

In this chapter we learned the absolute basics of interaction with a page using the DevTools. In the next chapter, you will learn how to extract data from it. We will collect the most popular websites on the internet from Amazon Alexa.