Category Archives: F12 Developer Tools

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Getting started with IndexedDB inspection in the Microsoft Edge DevTools – Microsoft Edge Dev Blog

The Windows 10 April 2018 Update introduced an all-new IndexedDB manager for the Microsoft Edge DevTools, allowing you to inspect your database, sort your data, and delete it—all from the Debugger. In this post, we’ll walk you through getting started with the new IndexedDB manager, and some improvements we have planned for the future!IndexedDB in the DevTools
Once you have created your database and added an object store, you can expand the IndexedDB node in the Resource picker in the Debugger to see a list of origins (the domain, application layer protocol, and port of a URL of the document where the script is being executed) from the resources loaded by the page. Your new database (or databases if you’re creating more than one) will be listed under the origin that created it, along with its object stores.

You can check out what’s in each object store by clicking on it, which will open it as a tab in the Debugger.

Managing IndexedDB data
When your app changes your IndexedDB data, you won’t see those changes in the DevTools in real time. You’ll need to click the Refresh button (or press Ctrl+F5) to update your object store or index.
The simple sample app searches images using the Bing Search API and saves those images as Base64 strings to an object store in an IndexedDB database. In the animation below, note that when we save an image, it won’t appear in our object store until we refresh (Ctrl+F5) in the IndexedDB manager.

Data in your object store or index can be deleted per row via the keyboard (Del) and context menus (right-click and select Delete item). You can also delete all IndexedDB data stored for the current user in Microsoft Edge using the Microsoft Edge Settings menu under “…” > Settings > Clear browsing data > Cookies and saved website data.
What’s next for the IndexedDB manager
In future releases, we’re planning to take all of the data storage solutions currently housed in the Resource picker in the Debugger—Local Storage, Cache, IndexedDB, etc.—and move them to a new tool we’re calling Storage. We think this change will make it easier and more intuitive to find, inspect, and manage web storage on your page in the DevTools.
Further our on our backlog, we’re evaluating a number of features for the IndexedDB manager:
Adding new data to an object store or index
Editing your existing key-value pairs directly
Making it easier to clear object stores or indices
Making it easier to clear all web storage solutions on your page
Adding blob support for IndexedDB in Microsoft Edge
Tell us what you think
We hope the IndexedDB manager makes the DevTools easier to use and improves your productivity in Microsoft Edge. If you encounter any bugs or have feature suggestions, the best way to flag them for our attention is via the Feedback Hub. You can launch the Feedback Hub straight from the DevTools using the icon (pictured below) in the top-right corner of the DevTools.

These features are available beginning with the Windows 10 April 2018 Update. If you want to get your hands on these (and other) improvements but aren’t yet on the April 2018 Update, check out the Microsoft Edge DevTools Preview App!
You can learn more in our docs, as well as in the IndexedDB content on MDN. As always, reach out to us with any questions, feedback, or feature requests on Twitter, Feedback Hub, or UserVoice.
– Zoher Ghadyali, Program Manager, Microsoft Edge DevTools
Updated July 11, 2018 10:42 am

Introducing the Microsoft Edge DevTools Protocol

Today’s web developers face more challenges than ever before. New frameworks spring up left and right. The number of devices capable of running the web multiply by the day. And we strive as creators to enable an inclusive and trustworthy world where fundamentals like accessibility, privacy, performance, and security are key to success.
These challenges are an opportunity for builders and consumers of devtools, requiring our solutions to enable innovation and scale. We need to provide web developers and tool vendors targeting Microsoft Edge, including other Microsoft teams, flexibility in solving these tough problems.
With the Windows 10 April 2018 Update, we’re taking the first major step on our journey by introducing the Microsoft Edge DevTools Protocol, a set of REST and JSON-RPC/WebSocket APIs, which enable clients to diagnose and debug Microsoft Edge tabs. In addition, we’ve worked with our teammates from Visual Studio, Visual Studio Code, and the Microsoft Edge DevTools to integrate with, and validate the interoperability of, these new capabilities within those apps.
In this post, we’ll elaborate on why we’ve taken this approach and the exciting progress we’ve made so far. We’ll provide resources throughout to help you get started using these new technologies. At the end, we’ll look at our next steps and share the many ways you can provide feedback to help us shape the future of the Microsoft Edge DevTools Protocol.
Get started with the new local and remote debugging scenarios with the new documentation from Requries the Windows 10 April 2018 Update or the Microsoft Edge DevTools Preview app.
Rebooting the Microsoft Edge DevTools platform
A year ago, we set out to re-architect the Microsoft Edge DevTools platform with two general customer scenarios in mind: growing the number of devtools that work with Microsoft Edge, and expanding support for debugging Microsoft Edge on new device form factors.
Expanding opportunities in local and remote scenarios is a key motivator for the new architecture. More details on the components in the diagram above are provided below.
To tackle the realities described above and achieve both local and remote support, we came up with a short but impactful list of guiding principles:
Decouple the platform and client components and release the client separately to allow for faster UX improvements and innovations
Build the platform interfaces on standard technologies to foster a larger ecosystem of devtools with support for Microsoft Edge
Build the platform in a way which allows devtools running locally to target instances of Microsoft Edge on remote Windows devices
Align with other browser vendors to support ecosystem portability and efficiency
This work will span multiple releases, but we’ve already made some exciting progress. Let’s dive in.
Decoupling the Microsoft Edge DevTools platform and client
To enable us to deliver customer value more rapidly, we first looked to take the Microsoft Edge DevTools app and ship it separately from the Windows OS as a Store application.
But to ship via the Microsoft Store, we needed to build only on APIs which are publicly available to others. This lead to the creation of the new Edge DevTools Protocol (EDP). The protocol is comprised of two sets of APIs: REST and JSON-RPC via WebSocket. Through EDP, devtools can build experiences around invoking methods and subscribing to diagnostics and debugger events.
The REST APIs are primarily used to discover information about EDP such as the version, available targets, and the supported API surface. All response values are formatted as JSON objects.
The WebSocket APIs are used to issue debugger and diagnostics commands and subscribe to correlated events. The APIs are broken down into Domains, which further break down into Methods, Events, and Types. A simple example would be the Debugger.setBreakpointByUrl API. A client would issue a JSON-RPC command looking something like this to set a breakpoint based on a JS file URL and location:
By switching to this publicly documented APIs, we’ve begun the process of shipping a new Microsoft Edge DevTools Preview app which runs in part on EDP. You can read more about the new DevTools Preview app here.
Fostering an ecosystem of Microsoft Edge DevTools
By decoupling the client from the platform, we’ve started the work to achieve our second goal of enabling an ecosystem of devtools which support Microsoft Edge. HTTP and WebSocket are ubiquitous technologies in native and web development environments. This means clients written in many programming languages can integrate. We hope this vastly reduces the barriers to entry for those who want to build devtools for Microsoft Edge.
In addition to calling APIs, from within those tools developers will need a way to launch the Microsoft Edge DevTools Server. We’re excited to announce that in the April 2018 update, we’ve introduced a new command line parameter and Edge UX for doing that. Check out the capture below for a preview of that experience:
The animated gif above shows the new Microsoft Edge DevTools server command-line launching functionality added in the Windows 10 April 2018 update.
These command-line parameters for launching the Microsoft Edge DevTools Server, along with available HTTP and WebSocket APIs, can be found in the Microsoft Edge DevTools Protocol documentation. Combined, these capabilities enable developers to more easily build devtools which target Edge.
To prove the viability of this approach, we on the Web Platform team partnered with the Visual Studio and Visual Studio Code teams to support F5 debugging of JavaScript running in a Microsoft Edge tab. We look forward to sharing more on that front soon!
Supporting remote debugging
In addition to wanting to foster a community of devtools which target Microsoft Edge, we want to enable those tools to target Microsoft Edge running on a remote Windows device. Though this specific scenario is not yet supported, it shows our long-term thinking:
Imagine you’re a HoloLens developer working with WebVR. Trying to debug your web app in Microsoft Edge on the HoloLens would likely be a time-consuming activity. Without a mouse and keyboard, navigating of devtools would be a cumbersome experience. Much better would be to run devtools on your local dev machine and remotely target Microsoft Edge instances running directly on the HoloLens.
To accomplish that, we built a plugin for the Windows Device Portal (WDP) which hosts the same Microsoft Edge DevTools Server that runs locally when launched via the command-line utility explained above. When you enable WDP in the Windows For developer settings, this will automatically install and activate the EDP plugin.
With your device in Developer mode and the Windows Device Portal turned on, the EDP plugin is automatically installed and HTTP and WebSocket servers started.
Using the Remote tab in the new Microsoft Edge DevTools preview app, you can connect to a remote device, view its targets, and connect to and debug them. You can read more about that here and here.
Note: At this point we support remote devices (and virtual machines) running the Windows 10 April 2018 Update or higher on PCs.
Aligning with the devtools protocol community
When we set out to build the devtools protocol for Microsoft Edge, we had a choice: build something which aligns with industry precedents or create our own approach tailored for our browser. The choice was obvious to us so we opted to align with the Chrome DevTools Protocol (CDP).
In the early winter of 2017, we met with fellow web experts from Google, Mozilla, Apple, VS Code, and others to discuss how better to align our work around devtools protocols. The result of that discussion is the DevTools Protocol Web Platform Incubator Community Group (WICG). Through this new group, we hope to publicly explore what alignment looks like and how best we as devtools protocol vendors can benefit the community.
Participants from Google, Mozilla, Microsoft, and VS Code drove the first draft of the WICG goals.
Separate from the WICG, we’ve worked hard as we’ve implemented EDP to validate that our API surface and method/event semantics mirror CDP. By releasing version 0.1 with support for three clients (Visual Studio Code, Visual Studio, and Edge DevTools preview app), we’ve achieved a high degree of interoperability. Where needed due to platform differences, we’ve introduced Microsoft Edge-specific methods and properties, all prefixed with ms and safely ignorable by any client not requiring them.
Lastly, though we’ve committed to testable interoperability, we know there will be bugs, and we hope you will help us find them! We look forward to your feedback as you build great devtools using EDP.
Next steps
This release is the first major step on a multi-milestone journey. We’re passionately committed to building the best Microsoft Edge developer tools and platform APIs to enable our customers to be more efficient and to fix bugs in Microsoft Edge. In terms of what’s next for EDP, here’s a quick look:
More devtools: we have more features to migrate to EDP within the Microsoft Edge DevTools, and are actively migrating the most-used tools to the new APIs. In parallel, we’re investigating how tools like Sonarwhal and WebDriver can integrate, as well.
More devices: the first release supports Windows Desktop SKU devices (including VMs of that flavor), and we plan to expand the Windows SKUs and devices supported for remote debugging.
Interop improvements: as more devtools on-board and we grow our API surface, we’ll continue to invest in ensuring we’re working with the larger DevTools Protocol community to align our efforts.
That’s a rough and quick run through our thoughts about the future. We’ll continue to evolve these priorities as we interact with our developer communities to build new platform capabilities together.
Providing feedback
If you’d like to provide feedback, we’d love to hear it and recommend several channels:
Feedback Hub: You can file feedback using the Microsoft Edge category and the Developer tools sub-category in the Feedback Hub app on Windows 10—just press Win+F to get started. Whether it’s a bug or suggestion, this is the easiest way for us to receive, track, and communicate around issues you bring to our attention.
Edge DevTools UserVoice: We monitor and use requests as an important signal informing what we do, and to help prioritize the order in which we implement new features. Please add requests or upvote your favorites.
Thanks for taking the time to learn about the new Microsoft Edge DevTools Protocol and our vision for a rich ecosystem of Microsoft Edge devtools. We hope you’re as excited as we are. Happy coding!
– Brendyn Alexander, Senior Program Manager

What’s new in Microsoft Edge in the Windows 10 April 2018 Update

The next update to Microsoft Edge is now available with the Windows 10 April 2018 Update! This update includes EdgeHTML 17, the next major version of Microsoft Edge’s rendering engine, as well as new features and everyday improvements across the product.
You can get your hands on the April 2018 Update today by checking for updates on your Windows 10 device, or, if you don’t have one, by downloading a free virtual machine from the Microsoft Edge Developer Site. You can also test Microsoft Edge for free in BrowserStack, which offers instant cloud-based manual and automated testing from a Mac or PC. BrowserStack will be updated to include the final release of EdgeHTML 17 in the coming weeks.
In this post, we’ll highlight what’s new in Microsoft Edge for users, and the new capabilities for site developers in EdgeHTML 17.
Better browsing: What’s new in Microsoft Edge
In every release, it’s our goal to make the web sing on Windows by making Microsoft Edge the fastest, easiest, and most productive place for you to enjoy your favorite sites and web apps. Below, you’ll find the biggest new features for Microsoft Edge.
Mute tabs with a click
We hear feedback every day that it’s too hard to find where audio is coming from, especially with lots of tabs open. In the April 2018 Update, the hunt to mute videos is over! When you hear unwanted audio playing in the browser, just press This tab is playing media  on the tab to turn the audio on or off.
Mute tabs with a single click
Our goal is to put users in control of autoplay content on the Web, so we’re continuing to explore more features to intelligently restrict autoplay audio and video content in future releases.
Automatically fill forms and credit card details
Microsoft Edge can now remember your name, credit card details, and other info when you’re signed in with a Microsoft Account. With your permission, we’ll save your form entries and give you the option to complete forms automatically.

Better reading with annotations, grammar tools, and more
We’ve overhauled the reading and Books experiences in Microsoft Edge, bringing a new, consistent, more powerful experience across all your documents, whether they’re EPUB or PDF books, documents, or web pages in Reading View.
The new reading experience uses Fluent Design System elements like motion and Acrylic material to provide a fluid, delightful experience that keeps the focus on the page.
In EPUB books and the Reading View for websites, you can now use the new Grammar Tools button to enable new comprehension aids. Grammar Tools can break the words on the page into syllables, as well as highlight different parts of speech such as nouns, verbs, and adjectives.

You can now also save EPUB books—whether downloaded from the web or purchased from the Microsoft Store—add bookmarks, and manage them all at the Books tab in the Microsoft Edge ”Hub” menu. You’ll also find suggestions there based on your reading habits.
For a distraction-free reading experience, you can now take books, PDFs, and Reading view pages full-screen. To enable full screen reading, just click the double arrow icon on the reading bar or press F11 on your keyboard.
Clutter-free printing
When printing a web page, you can now save paper by only printing the content you need. Select the “Clutter-free printing” option to print webpages without pop-ups and other unnecessary clutter.
Improved support for touchpad gestures
Microsoft Edge now supports custom multi-touch gesture support on devices with a precision touchpad, such as modern Surface laptops. On supported sites like Bing Maps, you can now use pinch-to-zoom and two-finger panning gestures to navigate maps just like you would on a touch screen.
Offline web sites and push notifications
Microsoft Edge now supports new web standards that allow web pages to send push notifications to your Action Center, even when the browser is closed. In addition, certain web pages can now work offline and improve performance, by using locally cached data when the cache is up to date, or when your device has a poor connection. You can learn more about these features in our post Service Workers: Going beyond the page.
New features for Extensions
We’re adding new extensions for Microsoft Edge every day, allowing users to customize their browsing experience with their favorite ad blockers, password managers, and more. To make it easier to find the extensions you’re looking for, Microsoft Edge will now show a dynamic list of suggested extensions under the “Extensions” menu.
Improvements for everyone
That’s just scratching the surface of what’s new in Microsoft Edge – you can learn more about these features at Microsoft Edge Tips, and see a list of everything that’s new over at the Microsoft Edge Changelog.
In every release, we make changes based on your feedback. Once you’ve tried out Microsoft Edge in the April 2018 Update, we want to hear what you think! You can send feedback on these features and suggestions for future improvements by selecting “Send feedback” from the “…” menu in Microsoft Edge.
Better basics: Improved performance and power efficiency
Windows users spend more time in web content than in any other activity on Windows. The Microsoft Edge engine powers not only the browser, but also powers web content throughout Windows—including in Windows apps and throughout the Windows shell itself—so performance and power efficiency is a major area of focus for the Microsoft Edge team in every release.
In the April 2018 update, we’re introducing dozens of optimizations that improve real, day-to-day performance and efficiency in every area of the product.
Making the browser more responsive
Input responsiveness is key to making the browser feel fast even when interacting with heavy websites or running on a busy system. In the April 2018 update, we’ve made improvements to make Microsoft Edge much more responsive on busy systems—such as when lots of other apps or background tasks are running.
Users will notice this most dramatically when something outside the browser such as a game or other high-impact application is busy in the background, which previously could cause input (such as typing) to be delayed, sometimes substantially dramatically.
Thanks to improved thread management in the April 2018 Update, this input will be more aggressively prioritized above background tasks, so Microsoft Edge will be much more responsive even when resources are limited.
We’ve also made improvements to responsiveness on busy pages. When the browser is busy with work that blocks user interactivity, we’ll more aggressively interrupt those tasks to put the user’s input first.
Better efficiency for an internet of GIFs
Regardless of how you pronounce them, GIFs are here to stay! In this update, we’ve dramatically reduced the power efficiency impact of rendering animated GIFs, especially on pages with lots of GIFs. Around 20 percent of pages loaded in Microsoft Edge include at least one GIF, so these improvements add up to even more battery life for Microsoft Edge compared to previous versions and to other browsers.
We’ve also made overall improvements to how we load images—on webpages with lots of images, we’ll now load the page noticeably faster by laying out page content without waiting to download the image in most cases.
Using resources more intelligently
Many web pages use resources continuously even when the user is not interacting or when the window is not in the foreground. When a tab is open for long periods of time, especially when lots of tabs are open, this impact adds up to reduced performance and battery life.
To prioritize the user experience, Microsoft Edge now intelligently suspends background tabs after the user has not interacted with them for a while, caching the content and suspending all CPU activity on that tab. This means improved performance and reduced power usage over time, with a minimal impact to the user experience. Tabs are then rapidly rehydrated when the user clicks on them. Our data from Windows Insiders previewing this feature shows that most suspended tabs are restored in less than half a second.
We’re also making foreground tabs more efficient. If a page is focused, but the user is not interacting with it (for example, scrolling or clicking links), Microsoft Edge will reduce the frame-rate of the tab to conserve power. This doesn’t impact video or 3D content on the page, and the browser will restore the full 60fps frame-rate as soon as the user interacts again.
New developer features for more engaging sites and web apps
The April 2018 Update brings with it EdgeHTML 17, our fifth major version of the Microsoft Edge rendering engine. This release brings powerful new developer capabilities for web sites and web apps, including the foundation for full-featured Progressive Web Apps on Windows.
A foundation for Progressive Web Apps
Starting in EdgeHTML 17, Service Workers and push notifications are enabled by default; you can learn more about these features in the blog post Service Worker: Going beyond the page. This completes the suite of technologies (including Fetch networking and the Push and Cache APIs) that lays the technical foundation for progressive Web Apps (PWAs) on Windows 10.

PWAs are simply web apps that are progressively enhanced with native app-like features on supporting platforms and browser engines, such as installation / home screen launch, offline support, and push notifications. On Windows 10 with the Microsoft Edge (EdgeHTML) engine, PWAs enjoy the added advantage of running independently of the browser window as Universal Windows Platform apps.
Beyond PWAs, Service Workers and the Cache API allow developers the ability to intercept network requests and respond from the cache. A website need not even been a full-blow web app to take advantage of the Service Worker cache for fine-tined page load performance and reliability, as well as the ability to provide an offline experience during periods of no internet or poor-quality connection.
Head over to our Progressive Web Apps docs to learn more about Service Workers and details about PWAs on Windows 10.
Expressive, performant typography with Variable Fonts
Full support for Variable Fonts, including CSS font-variation-settings and font-optical-sizing is available in EdgeHTML 17. Variable fonts enable developers to achieve the look of seemingly different typefaces with a single font by adjusting various axes – reducing the need for multiple font files and bettering performance.

Learn more about variable fonts and how to use them on your site at our Test Drive guide: Variable Fonts: An exploration of expressive, performant typography.
More powerful extensions
Microsoft Edge now supports the Notification API which displays notifications from extensions. Extension developers can now create different types of notifications (basic, list, image etc.) which support full user interaction. The notifications are also automatically logged into the Action Center. EdgeHTML 17 now also supports the Tabs.reload() method as part of the standard tabs API class.
Visit the notifications sample on how to use this API in your extension.
Improved accessibility via ARIA 1.1 Roles, States, and Events
EdgeHTML 17 now includes support for roles, states, and properties from the Accessible Rich Internet Applications (WAI-ARIA) 1.1 specification, including banner, complementary, aria-haspopup, aria-placeholder, and many more. Check out the Accessibility docs for more information about accessibility in Microsoft Edge.
Customizable multi-touch scrolling and gestures with Pointer Events
On devices with a Precision Touch Pad (PTP), Microsoft Edge will now fire Pointer Events with a pointerType of “touch” in response to PTP gestures.

This allows site developers to provide a customized multi-touch experience on modern Windows devices, including pinch-to-zoom and two-finger panning gestures, while preserving the highly optimized scrolling behaviors that users have come to expect from Precision Touch Pad devices.
CSS transforms on SVG elements
EdgeHTML 17 now supports CSS transforms on SVG elements and presentation attributes. This allows SVG elements to be visually manipulated, including rotating, scaling, moving, skewing, or translating.
More powerful developer tools
The tools have been updated with a number of major features, including basic support for remote debugging (via our new DevTools Protocol), PWA debugging features, IndexedDB cache management, vertical docking and more! We also continued the overall refactoring effort started last release as part of ongoing investments in performance and reliability.
You can learn more about what’s new in the Microsoft Edge DevTools at DevTools in the latest Windows 10 update (EdgeHTML 17).
Plugin-free screen sharing via the Media Capture API
Microsoft Edge now supports Screen Capture in RTC via the Media Capture API. This feature lets web pages capture output of a user’s display device, commonly used to broadcast a desktop for plugin-free virtual meetings or presentations. We’ll be sharing more about the Media Capture API in Microsoft Edge in an upcoming blog post.
Improved Web Security
EdgeHTML 17 introduces support for Subresource Integrity (SRI). Subresource Integrity is a security feature that allows browsers to verify that fetched resources (e.g. images, scripts, fonts, etc.) are delivered without unexpected manipulation.
Also new in EdgeHTML 17, the Upgrade-Insecure-Requests request header allows browsers to request a secure browsing experience. This header tells the server that the browser supports upgrading any insecure requests and the user should be redirected to a secure version of the site if available.
And lots more!
There’s too much EdgeHTML 17 for one blog post—you can see the full list of everything that’s new, including the full list of new APIs exposed in the DOM, over at the Microsoft Edge Dev Guide for EdgeHTML 17.
Get started testing EdgeHTML 17 today
You can get the April 2018 Update in a couple different ways. If you have automatic updates enabled, the update will be delivered to you when it’s ready for your device, starting today. Developers and advanced users who would like to get the update today can visit this blog post to learn how.
You can get started testing EdgeHTML 17 today on any device using free virtual machines from Microsoft Edge Dev. We’ve also partnered with BrowserStack to offer unlimited remote manual and automated testing in Microsoft Edge—BrowserStack will be adding EdgeHTML 17 in the coming weeks.
As with every release, we want to build our web platform in the open. We’ve updated our open platform roadmap at to reflect EdgeHTML 17, and encourage you to review and provide feedback on the features that matter to you.
You can reach our team directly via @MSEdgeDev on Twitter, or via the Feedback Hub app on Windows. We look forward to hearing what you think!
— Kyle Pflug, Senior Program Manager, Microsoft Edge
— Libby McCormick, Dev Writer, Microsoft Edge

Introducing the Microsoft Edge DevTools Preview app

Last fall at the Microsoft Edge Web Summit, we laid out our plans for rebooting the Microsoft Edge DevTools in response to your feedback.  Today we’re announcing the availability of the DevTools as a web app from the Microsoft Store. The new Microsoft Edge DevTools Preview app allows you to preview the very latest DevTools running side by side with the tools included in Microsoft Edge.
You can install the DevTools Preview app on Windows 10 Fall Creators Update or newer. Because the DevTools Preview app is based on the most recent Insider Preview version of the Microsoft Edge DevTools, this allows you to use the most recent updates to the Microsoft Edge DevTools without installing a full Insider release.
In addition, some new features will be exclusive to the app – such as debugging outside of the local browser, including web content in apps and remote debugging devices.
Debugging the web outside of the browser
When we think of the web, we largely think of browsers. But the web shows up on many more surfaces than just the browser in Windows: WebViews in apps, add-ins for Office, Cortana, Progressive Web Apps in the Microsoft Store, and many more places. The DevTools preview app gives you the ability to attach the tools to any instance of the EdgeHTML engine on Windows to debug.
The DevTools Preview app allows you to attach the Microsoft Edge DevTools to any local or remote EdgeHTML target.
Debugging remote devices
The web also runs on devices other than your dev machine. How would you debug the web on an Xbox, HoloLens, or an IoT device? One of the first features we’re previewing in the new DevTools app is remote debugging. By enabling Device Portal in the Settings app, you can now connect to that device over the network or via USB to debug remotely from the DevTools Preview app.

We’re previewing this with support for JS debugging of another instance of Microsoft Edge on another desktop device or VM. Over time, we’ll add support for the full set of DevTools against any EdgeHTML instance on any Windows 10 device. We’ll go into more detail on remote debugging in a future post.

Building a DevTools protocol for an ecosystem of tools
One of the biggest changes to the DevTools isn’t visible in a screenshot – the new Microsoft Edge DevTools Protocol. Previously, the Microsoft Edge DevTools worked via invasive native hooks into the EdgeHTML and Chakra engines.  This made it hard for other tools like VS, VS Code, Sonarwhal, and other open source tools in the ecosystem to support Microsoft Edge.
We started a conversation with other browsers last fall to incubate DevTools protocols at the W3C, with the goal of promoting interoperability between engines and allowing tools to support cross-browser debugging more easily.
The new DevTools app uses EDP to remotely debug Microsoft Edge today, and, eventually, all of our DevTools will use EDP. We’ll share more about EDP and our roadmap for additional tools in a future blog post.
The future of the Microsoft Edge DevTools
We’ve heard your feedback on the DevTools and we’re investing to make them great. Over the next several releases, we’ll evolve our tools based on your feedback. We encourage you to try out the DevTools Preview app, file feedback (just click the Smile icon in the DevTools), and reach out to us on Twitter with any comments!

We’ve got lots in store for the DevTools, including ongoing improvements in reliability and performance. With the Microsoft Edge DevTools Preview app, we can address your feedback faster and experiment with new ideas for the tools. We look forward to hearing what you think!
– Jacob Rossi, Principal PM Lead, Microsoft Edge DevTools

Breaking on DOM Mutations in the Microsoft Edge DevTools

Editor’s note: This continues the series we began last week, highlighting what’s new and improved in the Microsoft Edge DevTools with EdgeHTML 16.
As the web platform evolves, the line between web and application developers continues to blur. It’s common now for a web site to be more like a web app, with complex, single-page user interfaces built up by a combination of libraries and custom JavaScript code. This in turn has led to a web platform that requires more sophisticated tools to efficiently debug.
As we rely more and more on JavaScript to build up the DOM, and rely on tools that interact with and abstract away from us the nuances of DOMs across browsers, we lose the ability to easily know what caused a change to an interface node, especially if that change is unexpected. In EdgeHTML 16 (available with the Windows 10 Fall Creators Update), we’ve introduced the ability to break on mutations caused by any of the 450+ DOM APIs in the EdgeHTML platform and jump directly to the script that triggered the change.
For those who use Chrome DevTools, this will be a familiar and welcome addition to Edge debugging. It was our goal to implement and advance on a similar experience to make jumping between the two tools as seamless as possible. Read on for the changes you can expect in the Fall Creators Update (and can preview now via Windows Insider builds).
Breakpoint types
There are three breakpoint types:
Subtree modifications: when a node is added or removed from the subtree of the element on which the breakpoint is set
Node removal: when the node the breakpoint is set on is removed from the DOM tree
Attribute modifications: when an attribute of the node on which the breakpoint is set is modified
Setting and managing breakpoints
To set a breakpoint, right-click on a node in the DOM tree in the Elements tool. Under the DOM breakpoints item, you’ll see options to set and unset the supported breakpoint types.
Add new breakpoints by right-clicking a node in the DOM tree and selecting “DOM breakpoints.”
When you add a breakpoint, a red breakpoint indicator appears next to the node in the DOM tree. The breakpoint is also listed in the DOM breakpoints pane which exists in both the Elements and Debugger tools. You can disable and delete breakpoints by using the mouse to click the checkbox and delete icons, respectively. You can also right-click, or use the keyboard, on a breakpoint to invoke a context menu to apply the same actions:
Disable or delete breakpoints in the new DOM Breakpoints pane.
Triggering a breakpoint
A breakpoint is triggered whenever one of over 450+ DOM APIs are called by JavaScript. When the breakpoint triggers, you’ll jump to the Debugger tool with the file containing the triggering script opened and the line with the API call highlighted.
When a DOM API triggers a breakpoint, the Debugger tool will open with the API call highlighted.
In the Debugger tab, you’ll notice at the top of the call stack is an entry with the selector for the node the breakpoint was triggered on, and the type of breakpoint triggered.

Breakpoint persistence
We store breakpoints as part of your Edge DevTools settings and scope them to the URL of the page they’re set within. When you close and re-open Edge DevTools, or refresh the page, we’ll restore and attempt to automatically rebind the breakpoints to their respective DOM nodes. If we’re unable to automatically rebind them, we’ll indicate that they’re unbound in the UI with a warning icon on the breakpoint circle.
Breakpoints that cannot be rebound when the session is restored will show an alert icon in the Breakpoints pane.
You can use the context menus or shortcut icons in the DOM breakpoints panes to manually rebind any breakpoints we were unable to automatically rebind.
What’s next for DOM Breakpoints
We’re excited to launch this feature and hope to solve for as many developer scenarios as we can, but want to highlight a few gaps in the current implementation:
We don’t currently support rebinding breakpoints inside iframes. If you set a breakpoint in an iframe and close Edge DevTools or refresh the page, the breakpoint will be lost.
If your script encounters a synchronously-executed breakpoint before the DOM readyState is completed, you won’t be able to set a DOM breakpoint while the debugger is paused. You can typically remedy this situation by setting the defer or async script attributes.
For synchronous scripts, we trigger automatic rebinding of breakpoints when the window.onload event is called. In this case, we may miss binding breakpoints that would trigger during initial script-driven build-up of the DOM. For asynchronous scripts, we trigger a rebind attempt before the first script executes, so your breakpoints may rebind and trigger as desired.
We’re evaluating closing these gaps in future releases, as we continue to evaluate the prevalence of these scenarios. If you have feedback and find these unsupported areas to be blockers, please let us know!
Tell us what you think
We hope you enjoy this new addition and find it improves your productivity as you go about your developer workflows. If you find any bugs, please report them via the Feedback Hub. If you have questions or feature requests, don’t hesitate to leave a comment here, or reach out to us on UserVoice or Twitter.
— ­Brendyn Alexander, Senior Program Manager, Microsoft Edge DevTools

New and improved Event and CSS inspection for Microsoft Edge DevTools

Editor’s note: This is the first post in a series highlighting what’s new and improved in the Microsoft Edge DevTools with EdgeHTML 16.
EdgeHTML 16 is now rolling out to devices around the world as part of the Windows 10 Fall Creator’s Update—and with it, some great improvements to the Microsoft Edge DevTools.
In this post, we’ll walk through a slew of new updates to the Elements tab (formerly known as the DOM Explorer) with improvements to CSS at-rules, Event Listeners, Pseudo-Elements and the overall user experience.
CSS at-rules
In EdgeHTML 16, we’ve completely redesigned how at-rules appear in the Elements tab. Previously, usage of CSS at-rules were either missing or incorrectly displayed. The DevTools now show @supports, @media and @keyframes styles in separate sections within the Styles pane:

The new at-rules interface inspecting @keyframes on the CodePen example above
We also added a new pane for inspecting the rendered font of an element. In the Fonts pane, you can now see whether a font is served from the local machine or over the network and what, if any, fallback font face was used. If over the network, the DevTools will show the correlating @font-face rule:

You can now inspect the rendered font of an element in the Fonts pane.
Ancestor Event Listeners
The DevTools now allow you to inspect all event listeners on ancestor elements up to the current Window with the Ancestors option. You can also group event listeners by Element to see how the events will fire at each level of the element tree. This enables you to determine where a rogue event listener might be firing higher up the tree.

You can now inspect all event listeners on ancestor elements up to the current Window with the Acnestors option.
Ancestor Event Listeners can be grouped by Element or Event.
In the Styles pane, the DevTools now group styles by their respective pseudo-element, supporting ::before, ::after, ::first-letter, ::first-line and ::selection. This should make it easier to determine which style is winning the cascade.

Styles are now grouped by their respective psuedo-element.
User Experience
This release also includes some tweaks to the user experience of the DevTools to make it easier for developers who work in multiple browsers.
In particular, Layout pane has been removed and the box model is now at the top of the Computed pane, freeing up space for two new panes: Fonts and DOM breakpoints.

The box model is now at the top of the Computed pane.
Finally, to make it easier on developers who switch between multiple browsers, we’ve added two new ways to launch the DevTools: Ctrl+Shift+I and Ctrl+Shift+J. Ctrl+Shift+I will launch the DevTools just as the F12 keybinding does today. Ctrl+Shift+J will launch the DevTools (if not already open) and take you directly to the Console.
You can try out and file feedback for these new features starting with EdgeHTML 16, and find us on Twitter @EdgeDevTools to let us know what you think!
— Clay Martin, Program Manager, Microsoft Edge DevTools

Microsoft Edge Web Summit 2017 recordings are now available on Channel 9

Last week we welcomed hundreds of local developers and thousand of online viewers to our third annual Microsoft Edge Web Summit! Videos and slides from each session are now available to stream or download on Channel 9.
Learn about what’s new in EdgeHTML 16 in the keynote at Microsoft Edge Web Summit 2017.
Our sessions will bring you up to date on what’s in store for EdgeHTML 16, including learning how to use new and updated features like CSS Grid Layout, object-fit and object-position, WebVR, and the Web Payments API.

Learn about how to build faster websites with a fast and furious tour of web performance in the real world, and how to keep your development and testing on track with sonar, a new open-source, community-owned linting tool for the web. And make sense of the always-evolving web app landscape while blending the best of web and native with Progressive Web Apps.

Or go on a deep dive into the inner workings of the browser, to learn how we’re constantly rebuilding Microsoft Edge to be more secure, more accessible, and faster than ever, with every release we ship.

That’s just the beginning – there’s lots more to see on Channel 9, and we’ll have more to share about these topics and more in the coming weeks right here on the Microsoft Edge Dev Blog.
Thanks for joining us at Microsoft Edge Web Summit 2017 – we can’t wait to see you next year!
— Kyle Pflug, Senior Program Manager, Microsoft Edge