Opening Developer Tools
Before you can start troubleshooting, you need to know how to access Developer Tools. In most browsers, you can open it by pressing F12 or Ctrl + Shift + I on Windows/Linux, or Cmd + Option + I on Mac. You can also right-click on the page and select ‘Inspect’ or ‘Inspect Element’.
Console Tab: Identifying Errors
console.log: You can use
console.log("Value of x: ", x);
Sources Tab: Debugging Code
The Sources tab allows you to see the files that make up the current webpage.
- Setting Breakpoints: You can click on the line number in your code to set a breakpoint, which is a point where the execution will stop. This allows you to inspect the values of variables at that moment in time.
- Stepping Through Code: Once your code execution has stopped at a breakpoint, you can step through it using the controls in the Sources tab. This lets you see exactly how your code is executing, step by step.
Elements Tab: Interacting with the DOM
- Modifying Elements: You can also modify elements on the fly. This won’t change your actual code, but it’s a great way to test changes without having to refresh the page.
Network Tab: Monitoring Network Requests
- Viewing Network Requests: You can see all the network requests your page is making, along with status codes which can be useful for troubleshooting.
- Filtering Requests: You can filter by different types of content, or even search for a specific request.
Performance Tab: Analyzing Performance
If your code is running slowly, the Performance tab is where you should look.
- Recording a Session: Click the record button and interact with your page. When you’re done, stop recording, and you’ll get a detailed breakdown of what was happening.
- Analyzing Results: You can see how much time was spent on loading, scripting, rendering, and other tasks. This can help you identify bottlenecks in your code.