Update: As this is blowing up on Hackernews I added information to each of the tips in which environment they are supported in parenthesis after each heading. When I state “Chromium browsers”, this refers to all browsers that use the Chromium core and also feature all the Developer Tools. This is Chrome, Microsoft Edge, Brave and many more. As a reminder: Microsoft Edge is the browser that comes with Windows 10/11 and is based on Chromium and thus from a platform perspective simular to Chrome. They differ in UX and services around the core. Edge Developer Tools work closely with Google on bringing the work we add to the product back into the Chromium Core. But some of the things I am talking about here are experiments and exclusively in Microsoft Edge, which is available on Windows, Mac and Linux. Some functionality is only available inside Visual Studio Code via the Edge DevTools for VS Code extension .

This is a talk that I’ve given at CityJS this September. I am a principal product manager for developer tools in Microsoft Edge and these are things I encountered during working on the tools, documenting them and going through user feedback.

You can watch the recording of the talk on Youtube .

Here’s a write-up of all the things I covered:

1. Console is much more than `log()`!
(All browsers with developer tools following the standard)

There is no doubt that, besides the Elements tool, Console is the most used part of the browser developer tools. Specificially, people love to debug by putting a `console.log()` in their code to learn what’s going on. There are a few problems with that, and there are better ways to debug scripts, but as this is what people do, let’s talk how to make that experience better.

The first problem is log messages that aren’t removed when a product goes live clogging up the Console. Finding the information you’re looking for becomes daunting and the best way to work with that is to learn about the console filtering options available to you . Using these you can filter the reporting of the console to the things you care about and block out a lot of the noise.

What is that you’re logging?

The next problem with using `console.log()` is that we seem to only log values and forget to add where they come from. For example, when you use the following code, you get a list of numbers, but you don’t know what is what.

console.log(width)
console.log(height)

The easiest way to work around that issue is to wrap the things you want to log in curly braces. The console then logs both the name and the value of what you want to know about.

console.log({width})
console.log({height})

Adding to your console vocabulary

In addition to `console.log()` you have a lot more methods you can use . For example, `console.warn()` logs a warning, `console.info()` an informational message, and `console.error()` an error message. This not only results in slighty different displays in the console, but it also gives your messages a different log level, which means it is easier to filter for them.

Errors and assertions in Console

Displaying an error in the console is different to throwing an error, but it still is a good idea to show the severity of an issue to the person maintaining or debugging the product. Another interesting method is `console.assert()`, which only logs a message when a certain condition is met. Often you find yourself writing an `if` statement with a `console.log()` inside. Using `assert()` makes that one redundant and you have one less thing to worry about when cleaning up your debugging code.

Tracing where something came from

Often you find yourself adding a `console.log(‘called’)` or similar to test if a certain functionality is even triggered. Once you have that the next thing you normally want to find out what called that method. That’s what `console.trace()` is for, as it doesn’t only tell you that something was called, but also where the call came from.

Grouping console messages

If you have a lot to log, you can use `console.group(‘name’)` and `console.groupEnd(‘name’)` to wrap the messages in collapsible and expandable messages in the Console. You can even define if the groups should be expanded or collapsed by default.

Displaying and filtering lots of information in the console as tables

If you want to display a lot of of information as a log, it can become daunting to read the information. The `console.table()` method displays array-like data as a table in the console, and you can filter what you want to display by giving it an array of the properties you want to see.

For example, you can use `let elms = document.querySelectorAll(‘:is(h1,p,script’)` to get all H1, paragraph and script elements from the document and `console.table(elms)` to display this information as a table. As the different elements have a boatload of attributes and properties, the resulting table is pretty unreadable. If you filter down to what you are interested in by using `console.table(elms,[‘nodeName’, ‘innerText’, ‘offsetHeight’])` you get a table with only these properties and their values.

The table structure is maintained when you copy and paste this information, which makes it a wonderful tool to get data into Excel or Word, for example.

Blinging it up: $() and $$()

The console comes with a lot of convenience methods you can use called the Console Utilities . Two very useful ones are `$()` and `$$()` which are replacements for `document.querySelector()` and `document.querySelectorAll()` respectively. These not only return the nodeList you expect, but also cast the results to arrays, which means you can use `map()` and `filter()` on the results directly. The following code would grab all the links of the current document and return an Array with objects that contain only the `href` and `innerText` properties of each link as `url` and `text` properties.

$$('a').map(a => {
  return {url: a.href, text: a.innerText}
})

2. You can log without source access – live expressions and logpoints
(Chromium browsers)

The normal way to add a `console.log()` is to put it inside your code at the place you want to get the information. But you can also get insights into code you can’t access and change. Live expressions are a great way to log information without changing your code. They are also incredible to log values that change constantly without flooding the console and thus slowing down your product. You can see the difference in the following screencast:

Logpoints are a special kind of breakpoint. You can right-click any line in a JavaScript in the Sources tool of the Developer Tools and set a logpoint. You get asked to provide an expression you’d like to log and will get its value in the console when the line of code is executed. This means you can technically inject a `console.log()` anywhere on the web. I wrote about logpoints back in August and you can see a demo in the following screencast:

3. You can log outside the browser – VS Code debugger
(Chromium Browsers and VS Code)

When you start a debugging session in Visual Studio Code, you can spawn a browser instance and the Debug Console becomes the Console you are used to from the browser developer tools. I blogged about this in July in detail, so you can read up there how to do that . There is also more in the official documentation.

You can also watch this one minute video of me showing the functionality:

4. You can inject code into any site – snippets and overrides.
(Chromium Browsers)

Snippets are a way in Developer Tools to run a script against the current web site. You can use the Console Utilities in these scripts and it is a great way to write and store complex DOM manipulation scripts you normally execute in the Console. You can run your scripts in the window context of the current document either from the snippets editor or from the command menu. In the latter case, start your command with an ! and type the name of the snippet you want to run.

Overrides allow you to store local copies of remote scripts and override them when the page loads. This is great if you have, for example, a slow build process for your whole application and you want to try something out. It is also a great tool to replace annoying scripts from third party web sites without having to use a browser extension.

5. You can inspect and debug much more than you know!
(Chromium Browsers)

You may know the Chromium developer tools from browsers like Google Chrome, Brave or Microsoft Edge, but they are available in a lot more environments. Any app that’s based on Electron can have them enabled and you can use the Tools to peek under the hood and see how the product was done. This works, for example, in GitHub Desktop, Visual Studio Code, or you can even debug the Developer Tools of the browser using Developer Tools!

If you inspect the Developer Tools, you will see that they are written in HTML, CSS and TypeScript. It is an exciting environment to use these technologies, as you you know the rendering engine your code will run in – something you never know on the web.

Edge Developer Tools in Visual Studio Code
(Microsoft Edge via a VS Code extension)

The embeddable nature of the tools also allowed us to offer you a way to use them outside the browser. The Microsoft Edge Tools for Visual Studio Code extension brings the tools to Visual Studio Code. That way you can use the visual debugging tools right next to your code editor and you don’t need to jump between the two all the time.This also ties in with the “Console in Visual Studio Code” trick mentioned earlier. When you start a debugging session and you click the Developer Tools icon, the tools will open or – the first time – you will be prompted to install the extension.

6. Some dirty secrets…

Working intimately with developer tools and getting feedback and usage information taught me a few dirty secrets. The first one is that whilst we are all super excited about all the amazing features of developer tools, users only use a very small percentage of them. Many things heralded as the best thing since sliced bread in presentations and video tutorials are hardly every opened, let alone used. I thought this was about a lack of documentation and we spent a massive amount of time to update the DevTools documentation to ensure everything in them is described and explained, but that wasn’t it. Documentation is something people seem to go to as a last resort when they are stuck and Google/Stack Overflow/Social channels didn’t yield any results.

Developer tools have become complex and are overwhelming – a few ideas how to fix that
(Microsoft Edge)

It might be that the plain fact is that the Developer Tools of browsers grew organically over the years and can be incredibly overwhelming to look at. And that bothers me and I think we should do better. Here’s my mantra when it comes to tools for developers:

Developer tools should not expect people to be experts but turn them into experts over time.

We’re working on a few ideas to make that easier, and you will soon see those in Microsoft Edge. One idea we had is a “Focus Mode”. Instead of showing you all the tools and tabs we sorted the tools into different use cases, like “Elements/CSS debugging”, “Sources/JavaScript Debugging” or “Network inspection”. We then show only the relevant tools and hide all the ones that may be confusing or in the way.

Another feature we are working on are “informational overlays”. You get a help button that allows you to turn on overlays for the developer tools, explaining what each of the tools is, how to use it and providing links to the documentation. We hope that this would make it easier for people to learn about more features.

There is still a disconnect between authoring code and debugging the outcome
(Microsoft Edge)

Whilst it is amazing what tools provide us these days there is still a disconnect between authoring and debugging. Most of the time we write our code, create the app and then go to the browser to see what doesn’t work. We then use the browser developer tools to tweak and fix these issues. And then comes the big issue we still need to fix: how do you get the changes you created using the browser developer tools back into your code? Most of the time, the answer is “copy and paste or try to remember what needs changing”.

We’re currently working on two ways to make this easier. One is to replace the in-devtools editor with Visual Studio Code when it is available and to change files on the hard drive as you use the browser developer tools. The other is part of the VS Code extension and changes the source code in the editor as you use the developer tools but still gives you the final say in changing the file on disk. I described the problem and the possible solutions on the Edge blog or you can watch the following two screencasts to see them in action.

CSS Mirroring in Visual Studio Code:

What if… Visual Studio Code became the editor of in-browser Developer Tools?

7. You’re the audience and the clients of Developer Tools!
(Applies to all browsers, but channels shown here are Microsoft Edge only)

As a developer, you are the main audience for Developer Tools. We are open to your feedback and many of the recent changes to the tools are direct results from demands from outside developers. We try to make this as easy as possible by providing in-context ways to contact us directly. For example, the Visual Studio Code extension has prominent links and buttons for you to report issues and request features.

The source code of the extension is also on GitHub and you can file issues there.

The in-browser developer tools also have a direct button to give us feedback. To make it easier for you to provide actionable feedback, the button includes a lot of automatic information.

It records automatically what URL the issue happened on, takes a screenshot to include and offers to send diagnostic data. We also ask for you to provide an email in case we need more information and you can add attachments and info how to recreate the issue. We check this feedback daily, and a lot of great inventions and bug fixes came from that source.

The 1.4.0 release of the Microsoft Tools for Visual Studio Code brings a few highly requested features. We improved the screencasting feature, added device emulation and live issue reporting in your source code. You can check the 3 minute highlight reel here .

Improved screencasting

In previous versions of the extension, the screencast was a rudimentary feature tied to the panel of the extension. This didn’t give you much space to play with and the interactivity was limited. In this version, we moved the screencast to an own tab, which means that you can move it anywhere you want in your Visual Studio Code and use split panels. Furthermore, the screencast now supports developer tools overlays, which means you can see the padding and margin when navigating the HTML source and the inspector overlays.

Device emulation

One of the most requested features of the screencast was device emulation. People wanted to simulate different mobile devices without having to switch to the browser. Right next to the location field of the screencast you can now find a dropdown with a pre-populated list of mobile devices. You can select any of them and the viewport of the screencast will get resized accordingly. If the device is a touch device, you also get touch emulation, as indicated by the cursor changing to a filled circle. Next to the dropdown you also get a button to switch the device orientation.

Live inline issue reporting

The issues panel in browser developer tools shows you problems with accessibility, interoperability, performance and security. We considered moving this one to the extension, but thought we can do better. If your source code now has an issue, you will see a red underline under the line of code. You can hover over the line and you get information what the problem is, how to fix it and links to more documentation. You can also navigate all the issues in the current document or use the problems tab in the lower panel to see all issues in the current workspace.

Get the extension

The extension is available for all major platforms from inside Visual Studio Code and on the marketplace. The source is also available on GitHub and we invite anyone to file issues you encounter. Some of the functionality is dependent on you having an installation of Microsoft Edge Canary and you need to have Node/NPM installed on your machine.

Starting with the next version of Microsoft Edge, we are running an experiment that allows you to use Visual Studio Code as the editor of the in-browser Developer Tools. Here’s a three minute video explaining why we think this is a good idea.

Developer Tools have excellent visual tools that allow you to tweak and debug front-end code. The problem is that the changes aren’t synced and once you reload the page, all is lost. Workspaces are a feature to work around that issue and I blogged about those some time ago. We wanted to use the sync capabilities of Workspaces and replace the in-built editor in the Sources tool with Visual Studio Code, effectively giving you the convenience of the editor you are used to and the visual tooling the browser DevTools provide.

To this end, we came up with a new way to invoke a Workspace and make VS Code the editor of the browser. It is an experiment you need to turn on in DevTools by choosing the gear icon.

Once you enabled the “Open source files in Visual Studio Code” experiment, the browser will automatically detect when you work on a local file or local server.

It then prompts you to define the root folder of this file and tell DevTools where to find it.

You can get more information, or skip setting up the functionality. Once you pressed the “Set Root Folder”, you can pick the folder using Finder or Explorer (or whatever other file manager you use).

Once chosen, DevTools needs access to this folder to write files to it.

If you grant DevTools access, activating any link in the tools will now open the folder with all the files in Visual Studio Code instead of the in-built editor in the Sources tool.

You get a new instance of VS Code and the file opens on the correct line.

Any of the changes you do now to the CSS in DevTools changes the file and is reflected inside VS Code. If you do a change in VS Code and save the file it also syncs live in the browser.

You can change the settings of the experiment to not open files in VS Code and to not live sync the changes.

You can read more about this on the official docs and we’d love to hear what you think of it. You can comment on Twitter at @EdgeDevTools or use the feedback mechanism built into the tools directly.

Summary: With the release of 1.3.1 of the Edge Tools for VS Code we introduce a better way to get changes you made in the Styles tool back into your source code. We’d love to know what you think of it and what we can do better. There’s a GitHub issue dedicated to feedback.

Developer Tools in browsers are a fantastic way to debug, edit and tweak the CSS of your web product. You get detailed insights into what CSS is applied to which element, and you get visual tools to aid you on your journey to create a beautiful and working interface.

The big drawback of Developer Tools is that you do not work on the source code of your product, but instead you work with what the browser created from these source files. This means that whilst you can change the code that runs in the browser to find out what needs to get fixed, you are not actually fixing the source code. You are debugging, not developing.

One of the unanswered questions of this process is how you get the changes to your styles back into your source files. The current solutions are suboptimal, as they mean you copy and paste what you created using the browser developer tools.

There is a bit of help available. Chromium based browsers like Microsoft Edge or Chrome have a Changes tool, which shows you what you changed in each file:

Firefox has a live version of this that changes whilst you tweak your CSS and has a “copy all changes” button that results in a CSS document with helpful comments.

Another existing process is that you can set up a Workspace in Developer tools, which means that any change to the styles will also change the source file on the hard drive.

This solution has the problem that you are constantly changing the files. This can have annoying side effects if you’re using a live reload server. And – even more importantly – it means that you have to undo all the changes you made during debugging. Often you will make a lot of changes until you end up at the desired outcome.

With the browser developer tools inside Visual Studio Code, we have a new environment to think about this issue and we would love to hear what you think of the solution we have right now in the Edge DevTools for VS Code extension which we call CSS mirror editing.

When mirror editing is enabled, any change to the CSS done in the Styles editor will also reflect in the source document. However, the document is not automatically changed, which means it doesn’t trigger any live server or watchers on the folder. Once you are happy with all the changes you did, you can save the document.

You can enable and disable Mirror Editing using the button in the extension side bar for now. We are looking into a few better ways to place this, and would like to know what would be best for you.

We would love to hear from you about the feature and what we could do differently. The best way to do that is to add to the Issue on GitHub provided as a link in the CSS Mirror Editing Sidebar.

When using the Edge DevTools for VS Code extension inside the editor, one thing that I kept doing wrong was opening files accidentally next to the tools.

By default, the tools show up as their own pane next to the main editor. This is an editor pane of VS Code, and thus supports many things, including tabs.

When I use the tools, this group has focus. And when I go open another file to edit, it opens as a new tab next to the tools. Many a time this messed up my screencasts.

The trick is to lock the group with the tools in them. You do that by activating the … menu of the tools pane and select “Lock Group”.

The locked group then shows a lock icon and no other files will open as tabs on it, even if it had the focus.

You can see this in action in the following screencast.