Testing Websites in Chromium Edge: A How-To

Microsoft Edge is now built on Chromium, meaning it shares the same core engine as Google Chrome. This makes it an essential browser for web developers and testers to verify that sites work correctly for a large segment of users. This guide walks you through the built-in developer tools and features in Edge that let you inspect, debug, and test your website effectively, covering everything from basic device emulation to performance checks.

What You’ll Need

• A computer with Microsoft Edge installed (the Chromium version, which is the standard on Windows 10/11 and available for macOS and Linux).
• The website you want to test, either hosted locally (e.g., localhost) or on a live server.
• Familiarity with basic web concepts like HTML, CSS, and JavaScript is helpful but not strictly required.

Step-by-Step

1. Open DevTools: Navigate to your website in Edge. Right-click anywhere on the page and select “Inspect” from the context menu. Alternatively, press F12 or Ctrl+Shift+I (Windows/Linux) or Cmd+Option+I (macOS). The DevTools panel will open, usually docked to the right or bottom of the window.
2. Explore the main panels: Familiarize yourself with the tabs at the top of DevTools. The most commonly used are:
   • Elements: Shows the HTML and CSS. You can edit styles live and see changes instantly.
   • Console: Displays JavaScript errors, warnings, and lets you run JavaScript commands.
   • Sources: Shows all files loaded by the page. You can set breakpoints here to debug JavaScript.
   • Network: Shows all network requests (images, scripts, API calls) with timing and status codes.
   • Performance: Records and analyzes runtime performance, helping you find jank or slow parts.
   • Application: Inspects storage like cookies, local storage, and service workers.
3. Test responsiveness with Device Toolbar: Click the “Toggle Device Toolbar” icon (a rectangle with a phone outline) in the top-left of DevTools, or press Ctrl+Shift+M. This switches to a mobile emulation view. From the dropdown at the top, you can select specific devices like an iPhone or Pixel, or set a custom screen size. The page will re-render at that viewport width, letting you check your responsive design.
4. Simulate network conditions: In the Device Toolbar, or under the “Network” tab, you’ll find a “Throttling” dropdown (usually showing “Online”). Select “Slow 3G” or “Fast 3G” to see how your site loads on slower connections. This helps identify large images or scripts that delay page load.
5. Inspect and edit CSS: Go to the “Elements” tab. Click the arrow icon (inspect tool) in the top-left corner of DevTools, then click an element on the page. The HTML is highlighted, and the “Styles” pane on the right shows all CSS rules applied. You can uncheck boxes to disable styles, or click on values and type new ones to see changes immediately. This is great for tweaking colors, spacing, and fonts without reloading.
6. Debug JavaScript: Open the “Sources” tab. Find your JavaScript file in the file tree on the left. Click on a line number to set a breakpoint (a blue arrow appears). Reload the page or trigger the action that runs the script. Execution will pause at the breakpoint, and you can inspect variables in the “Scope” section, step through code using the buttons (Step Over, Step Into, etc.), and see the call stack.
7. Monitor network requests: Open the “Network” tab and reload the page. You’ll see a list of every request. Click on any request to see details like headers, preview, response, and timing. Look for requests that fail (shown in red) or take a long time. The “Status” column shows HTTP codes (200 is OK, 404 is not found, 500 is server error).
8. Check performance: Open the “Performance” tab. Click the record button (circle icon), then reload the page or interact with it, and click “Stop”. You’ll get a detailed timeline showing frames, scripting, rendering, and painting. Look for long red blocks in the “Main” thread, which indicate tasks that block the UI. The “Summary” tab below shows which activity took the most time.
9. Test with different Edge features: Edge has some unique testing tools. In the “Elements” panel, you can use the “Accessibility” tab to check for basic accessibility issues. Also, try the “Rendering” tab (find it by pressing Ctrl+Shift+P to open the command menu, then type “Rendering”). Here you can emulate CSS features like prefers-color-scheme (dark mode) and disable JavaScript to see how the page behaves without it.
10. Use Edge’s built-in screenshot tools: To capture a full-page screenshot, click the three-dot menu in DevTools (top-right), then select “Capture full size screenshot”. This is useful for visual regression testing or sharing with your team.

Common Mistakes

• Forgetting to reload after changes: When you edit CSS or JavaScript in DevTools, changes are temporary and lost on reload. Always save your edits in your source code and then reload to verify.
• Testing only at desktop widths: Many developers check their site only on their own screen size. Always test at multiple widths, especially small mobile sizes, to catch layout breaks.
• Ignoring the console: JavaScript errors often appear only in the console. If the page seems broken, always check the console first for red error messages.
• Not using incognito for testing: Extensions and cached data can interfere with testing. Use InPrivate mode (Ctrl+Shift+N) to get a clean slate.
• Assuming emulation equals real device: Device emulation in DevTools is not a substitute for testing on a real phone or tablet. It approximates viewport and touch events, but not the actual hardware performance or browser differences.

Tips

• Use the Command Menu: Press Ctrl+Shift+P in DevTools to open a searchable command menu. You can quickly toggle settings like “Disable cache” or “Capture full size screenshot” without digging through menus.
• Customize device list: In the Device Toolbar, click “Edit” to add your own custom devices with specific screen sizes and pixel ratios.
• Use local overrides: In the “Sources” tab, right-click a file and select “Override content”. This lets you make changes to a file that persist across reloads, even on live sites, which is great for testing fixes before applying them to your codebase.
• Leverage the “Network” tab’s “Disable cache” option: While testing, enable this (check the box) to ensure you’re always loading the latest files, not stale cached ones.
• Learn keyboard shortcuts: Ctrl+Shift+C to inspect an element, Ctrl+Shift+F to search across all files, and Ctrl+Shift+E to open the Console with a prompt.

Troubleshooting

• DevTools won’t open: Try pressing F12 again or using the menu: click the three dots in the top-right of Edge, then “More tools” > “Developer tools”. If it still doesn’t work, restart Edge.
• Changes in Elements don’t reflect: Make sure you’re editing the correct element and that the CSS rule isn’t overridden by a more specific rule. Check the “Styles” pane for strikethrough text indicating overridden properties.
• Breakpoints are not hitting: Ensure the file you’re debugging is the one actually loaded (check the “Sources” tab for the correct file). Also, make sure you’re not in a minified file; use the “Pretty print” button ({} icon) to format it.
• Network requests fail: Check the “Status” code. A 404 means the file isn’t found; 500 is a server error. Also, look at the “Initiator” column to see what caused the request. If it’s a CORS error, the console will show a specific message.
• Performance recording shows nothing: Make sure you click the record button before interacting with the page. Also, the recording stops automatically after a few seconds; you can adjust this in the settings.
• Device emulation looks wrong: Try a different device from the list or manually set width and height. Also, check that “Responsive” mode is selected if you want to drag the edges.

Frequently Asked Questions

1. Is Edge’s DevTools the same as Chrome’s?
   
   Yes, they are nearly identical since both are Chromium-based. There are a few Edge-specific additions, but the core features are the same.
2. How do I test a local website with Edge?
   
   Just navigate to http://localhost or whatever address your local server provides. Edge can access localhost without any special setup.
3. Can I test mobile-specific features like touch events?
   
   Yes, the Device Toolbar simulates touch events. You can also use the “Sensors” panel (via the Command Menu) to emulate device orientation and location.
4. How do I see what a site looks like in dark mode?
   
   Open the “Rendering” tab (via Command Menu) and select “prefers-color-scheme: dark” from the “Emulate CSS media feature” dropdown.
5. What is the fastest way to find a specific element in the code?
   
   Right-click the element on the page and select “Inspect”. This will jump to the correct HTML in the Elements panel automatically.
6. Can I test in Edge without affecting my normal browsing?
   
   Yes, use InPrivate mode or create a separate browser profile for testing. This isolates your testing from your regular browsing data and extensions.

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