How to Open Chrome DevTools for Debugging and Monitoring

To open Chrome DevTools for debugging and monitoring, you can use the keyboard shortcut Ctrl + Shift + I (Windows/Linux) or Command + Option + I (Mac).

Pressing this shortcut will open the DevTools panel on the right side of the browser window.

You can also right-click on a page element and select Inspect to open the DevTools panel.

This will allow you to inspect the HTML, CSS, and JavaScript code behind the element.

Using Chrome DevTools is a game-changer for web developers. You can do everything from testing the viewport on a mobile device to editing a website on the fly. To use the latest version of the developer tools, you may want to use Chrome Canary, which is the experimental version of Chrome that is updated nightly.

Chrome Canary can be run side by side with Chrome so you can check any issues that may arise. You can also enhance your development by going to chrome://flags and enabling the Developer Tools experiments feature. This allows you to use the settings panel in developer tools to toggle individual experiments.

To open the developer console in Chrome, you'll need to click the three-dots icon in the upper-right-hand corner of the browser window. Alternatively, you can use the Chrome dev tools hotkey: F12 (on Windows/Linux), and Option + ⌘ + J (on macOS). This will open the console at the bottom or on the right of the Chrome page.

The Chrome DevTools provide a range of features, including a device preview, JavaScript debugger, network panel, inspector tool, console, and performance panel. Here are some of the key features:

These features make it easy to identify and fix issues with your website, even if you don't have coding experience.

You can use Chrome DevTools for non-development purposes, like testing your website's responsive design on different devices. This is especially useful if you're not a developer but still want to ensure your website looks great on various devices.

The device preview feature allows you to test your webpage's responsive design, giving you a real-time view of how it will look on different devices, such as desktops, tablets, and smartphones.

You can also use the console to identify page errors and warnings, which is helpful for non-developers who want to troubleshoot issues with their website.

The performance panel is another useful feature, as it allows you to check your website's performance, including page speed, without needing to write any code.

Here are some key features to explore in Chrome DevTools for non-development uses:

Monitoring the protocol is especially handy to understand how the DevTools frontend makes use of the protocol. You can view all requests/responses and methods as they happen.

To enable the Protocol Monitor, click the gear icon in the top-right of the DevTools, select Experiments, turn on "Protocol Monitor", then close and reopen DevTools. Now click the ⋮ menu icon, choose More Tools and then select Protocol monitor.

You can issue your own commands using Protocol Monitor. Type the command into the prompt at the bottom of the Protocol Monitor panel and press Enter, for example, Page.captureScreenshot. If the command requires parameters, provide them as JSON, for example, {"cmd":"Page.captureScreenshot"",args":{"format": "jpeg"}}.

Setting JavaScript breakpoints can be a lifesaver when debugging code. Click on the line number you want to break at, then press Cmd + R (Ctrl + R) to refresh the page, and the page will run right to that breakpoint.

Using Chrome DevTools is a great way to set these breakpoints.

Monitoring the protocol is a powerful tool for understanding how the DevTools frontend works. You can view all requests and responses as they happen.

Click the gear icon to open the Settings panel and select Experiments. Turn on "Protocol Monitor" and close and reopen DevTools. Now you can access the Protocol Monitor panel.

The Protocol Monitor panel allows you to issue your own commands. If a command doesn't require parameters, simply type it into the prompt and press Enter. For example, you can use Page.captureScreenshot.

If a command requires parameters, provide them as JSON. For instance, you can use {"cmd":"Page.captureScreenshot"",args":{"format": "jpeg"}}. This will allow you to capture a screenshot in JPEG format.

You can also use the command editor to create a structured form for editing parameters and viewing their documentation and types. This is especially useful for complex commands.

Alternatively, you can execute commands from the DevTools console. First, open devtools-on-devtools, then use Main.MainImpl.sendOverProtocol() in the console.