Validation & Tools
Learn how to debug, validate, and perfect your HTML using professional developer tools.
Code Quality & Validation
Validation ensures your code follows the official rules of HTML, which helps with browser compatibility and accessibility.
- W3C Validator : The official World Wide Web Consortium tool that checks for syntax errors and non-standard tags.
- HTML linting : Tools (like ESLint or HTMLHint) that run inside your code editor to catch mistakes as you type.
- The Nu Html Checker : The modern version of the W3C validator used for checking HTML5 documents.
Browser Developer Tools
Every modern browser comes with a suite of tools that allow you to dissect any website on the internet.
- Inspect element : A live tool that lets you view and edit the current DOM and CSS styles in real-time.
- View source : Displays the raw HTML file as it was received from the web server.
- Browser DevTools : The complete panel (F12 or Ctrl+Shift+I) used for debugging performance, network requests, and code structure.
Browser DevTools Workflow
How to use the built-in inspector to verify your HTML structure and accessibility.
/* Pro Tip: Use DevTools to test accessibility */
1. Right-click any element.
2. Select 'Inspect'.
3. Look for the 'Accessibility' tab in the elements pane.
4. Check if the element has a computed name and role.Professional Debugging
When your layout breaks, follow these steps to find and fix the issue quickly.
- Check for unclosed tags : Use a linter to find tags that are missing their closing counterpart.
- Verify attribute quotes : Ensure all attributes are wrapped in quotes to avoid parsing errors.
- Check the Console : Look for errors in the 'Console' tab of DevTools that might be related to script loading or missing assets.
Knowledge Check
1. What is the official service used to check if your HTML follows the latest web standards?
2. Which browser feature allows you to see the original, unformatted HTML code sent by the server?
3. What does an 'HTML Linter' do during development?
4. How does 'Inspect Element' differ from 'View Source'?
5. Why is validating your HTML important for SEO?
6. In Browser DevTools, which tab allows you to modify HTML elements and see changes in real-time?