Chrome DevTools Debugging Examples

Explore practical examples of using Chrome DevTools for debugging common web development issues.
By Jamie

Introduction to Chrome DevTools for Debugging

Chrome DevTools is an essential toolset for web developers, offering a variety of features for debugging, optimizing performance, and analyzing web applications. By utilizing these tools, developers can gain insights into their code, troubleshoot errors, and enhance user experience. Below are three diverse examples of using Chrome DevTools for debugging, showcasing practical use cases and step-by-step instructions.

Example 1: Inspecting Network Requests

Context

When developing a web application, it’s common to encounter issues with network requests, such as API calls not returning the expected results. Understanding how to inspect these requests can help identify and resolve issues quickly.

Example

  1. Open Chrome and navigate to your web application.
  2. Right-click on the page and select Inspect to open DevTools.
  3. Navigate to the Network tab.
  4. Reload the page (F5) to capture network activity.
  5. Filter the requests by selecting XHR to view only API calls.
  6. Click on any request to see detailed information, including request headers, response, and timing.
  7. Analyze the Response tab to check if the data returned from the server matches your expectations.

Notes

  • Use the Preserve log checkbox to keep network requests even after navigation.
  • This method is invaluable for debugging issues related to data fetching and API responses.

Example 2: Debugging JavaScript Errors

Context

JavaScript errors can often lead to broken functionality on a webpage. Using DevTools, developers can quickly identify and fix these issues in their scripts.

Example

  1. Open your web application and launch DevTools.
  2. Navigate to the Console tab, where you’ll see any JavaScript errors logged.
  3. Click on the error message; it will display the line number and file in which the error occurred.
  4. Switch to the Sources tab and locate the file and line number indicated in the error message.
  5. Set a breakpoint by clicking on the line number in the source code. This allows you to pause execution at that point.
  6. Interact with your application to trigger the code execution and observe the variables in the Scope section of the right sidebar.
  7. Step through the code using the Step over button to investigate how the error arises.

Notes

  • Console errors can also provide stack traces to help trace back the origin of the error.
  • Use the Watch panel to monitor specific variables as you debug.

Example 3: Analyzing CSS Styles

Context

CSS issues can lead to layout problems that affect user experience. Chrome DevTools allows you to inspect and modify CSS in real-time, making debugging easier.

Example

  1. Open your webpage and right-click on the element with a styling issue.
  2. Select Inspect to open DevTools with that element highlighted in the Elements tab.
  3. In the Styles pane on the right, review the CSS rules applied to the selected element.
  4. Modify the CSS properties directly in the panel to see changes reflected in real-time.
  5. Use the Computed tab to view all computed styles for the element, which helps identify overridden styles.
  6. If necessary, locate related stylesheets or media queries affecting the element’s appearance.

Notes

  • You can toggle styles on and off by unchecking the boxes next to each property.
  • The :hov button allows you to simulate hover states for better visual debugging.

By employing these examples of using Chrome DevTools for debugging, developers can enhance their workflow, identify issues efficiently, and ultimately improve the quality of their web applications.