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The filter was missed in unit testing and didn't actually work correctly. In most cases this didn't lead to a visible failure, but this fixes it.

Fixes #1704

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April 20, 2021 13:29
October 16, 2020 11:55
January 26, 2021 16:28
July 25, 2019 13:23


This is a DAP-based JavaScript debugger. It debugs Node.js, Chrome, Edge, WebView2, VS Code extensions, and more. It has been the default JavaScript debugger in Visual Studio Code since 1.46, and is gradually rolling out in Visual Studio proper.

Nightly Extension

The shipped version of VS Code includes the js-debug version at the time of its release, however you may want to install our nightly build to get the latest fixes and features. The nightly build runs at 5PM PST on each day that there are changes (see pipeline). To get the build:

  1. Open the extensions view (ctrl+shift+x) and search for @builtin @id:ms-vscode.js-debug
  2. Right click on the JavaScript Debugger extension and Disable it.
  3. Search for @id:ms-vscode.js-debug-nightly in the extensions view.
  4. Install that extension.

What's new?

In js-debug we aim to provide rich debugging for modern applications, with no or minimal configuration required. Here are a few new features that js-debug brings:

Debug child process and workers

In Node.js, child processes will automatically be debugged. In browsers, service workers, webworkers, and iframes will be debugged as well.

While debugging workers, you can also step through postMessage() calls.

Debug Node.js processes in the terminal

You can debug any Node.js process you run in the terminal with our revamped Auto Attach. If auto attach isn't on, you can run the command Debug: Toggle Auto Attach to turn it on. Next time you run a command like npm start, we'll debug it.

Once enabled, you can toggle Auto Attach by clicking the Auto Attach: On/Off button in the status bar on the bottom of your screen.

You can also create a one-off terminal for debugging via the Debug: Create JavaScript Debug Terminal command.

In the previous debugger, you had to remember to add the --inspect flag when you ran a command, and couldn't hit breakpoints early in the program since attachment was asynchronous.

Profiling Support

You can capture and view performance profiles natively in VS Code, by clicking on the button in the Call Stack view, or through the Debug: Take Performance Profile command. The profile information collected through VS Code is sourcemap-aware.

Easy npm script debugging

You can debug npm scripts by clicking the code lens shown in the package.json, or by running the Debug: Debug NPM Script command/

You can configure where and if the code lens is displayed in the debug.javascript.codelens.npmScripts setting.

Automatic browser debugging

By default, any links you click through the JavaScript debug terminal (Debug: Create JavaScript Debug Terminal command) will open in debug mode. If you'd like, you can enable this for all terminals, or disable it, by setting debug.javascript.debugByLinkOptions to always or off, respectively.

Instrumentation breakpoints

When debugging web apps, you can configure instrumentation breakpoints from VS Code in the "Browser Breakpoints" view.

Better autocompletion in debug console

Autocomplete in the debug console has been significantly improved. You can expect better suggestions for more complex expressions than VS Code was able to handle before.

Return value interception

On a function's return statement, you can use, inspect, and modify the $returnValue.

Note that you can use and modify properties on the $returnValue, but not assign it to--it is effectively a const variable.

Top-Level await

You can use await at the top level in the debug console.

However, like the Chrome devtools, if you use await while paused on a breakpoint, you'll only get a pending Promise back. This is because the JavaScript event loop is paused while on a breakpoint.

Pretty-print minified sources

The debugger can now pretty print files, especially useful when dealing with minified sources. It will show a prompt when you step into or open a file that looks minified, and you can also trigger pretty printing manually via the Debug: Pretty print for debugging command.

Click to view gif

You can turn off the suggestion prompt by selecting Never, or changing the setting debug.javascript.suggestPrettyPrinting to false.

Support for Microsoft Edge and WebView2

We support launching the new Microsoft Edge browser, via the pwa-msedge debug type. It supports all the same configuration settings as chrome does.

With this comes support for the WebView2 control in desktop Windows applications. Check out our webview demo to learn how to set this up.

Better sourcemap and breakpoint behavior

Js-debug has a rewritten suite of sourcemap handling and breakpoint resolution logic. This results in more reliable breakpoint behavior in more cases. For example:

  • We are guaranteed to set breakpoints before hitting them, where there were previously scenarios where this did not happen.
  • We can handle sources present in multiple compiled files. This is common when dealing with split bundles in web apps.
  • We now support in-place transpilation (such as ts-node and @babel/register).

Copy values in call stack view

VS Code has long had an action to "Copy Value" from the Variables view. However, previously this was truncated for object or long values. Changes in VS Code and js-debug allow us to losslessly copy the full expressions as JSON.

Other small things

js-debug is a cleanroom rewrite of a JavaScript debugger, so there are a large number of small improvements. Here are some more that are unworthy of their own heading:

  • Console output is now improved. Promises, ArrayViews/ArrayBuffers, and other complex data structures are better supported.
  • Logpoint breakpoints now support complex expressions and statements. Errors thrown will be printed, rather than silently eaten.
  • You can now specify partial versions in the Node.js runtimeVersion. Previously you needed to specify the full version, such as 12.3.4. Now, you can specify 12 and we'll use the most recent 12.* installed on the system.
  • Sourcemaps are now supported when attaching via the Attach to Node.js Process command.
  • Several improvements have been made for faster performance and better out-of-the-box behavior in monorepos and multi-part applications.
  • The set of APIs are now supported.
  • You can pass stable, canary, or dev as runtimeExecutables when launching browsers. We'll do our best to discover and use the specified version on your machine.
  • You can now set the Node.js program to files with other or no extensions without workarounds.
  • Restart frame requests are now supported.
  • Command line APIs like inspect() and copy() are now available.