Visual Studio Code For Javascript

:rotating_light: Important

Autocompletion works because Visual Studio Code uses TypeScript behind the scenes - even for JavaScript - to provide type information that can then be used to inform the completion list as you type. Visual Studio Code is able to detect that this is a Node.js project, and as a result, automatically downloaded the TypeScript typings file for Node. Visual Studio offer the open tools & flexibility you need to create & deploy web applications. Use our best code editor for HTML5, CSS3, & JavaScript today.

Please file issues on the repo for the new js-debug extension. By default, this extension now delegates to that one which is built-in to VS Code.

Debug your JavaScript code running in Google Chrome from VS Code.

A VS Code extension to debug your JavaScript code in the Google Chrome browser, or other targets that support the Chrome DevTools Protocol.

Supported features

Setting breakpoints, including in source files when source maps are enabled
Stepping, including with the buttons on the Chrome page
The Locals pane
Debugging eval scripts, script tags, and scripts that are added dynamically
Watches
Console

Unsupported scenarios

Debugging web workers
Debugging Chrome extensions
Any features that aren't script debugging

Getting Started

Open the folder containing the project you want to work on.

Using the debugger

When your launch config is set up, you can debug your project. Pick a launch config from the dropdown on the Debug pane in Code. Press the play button or F5 to start.

Configuration

The extension operates in two modes - it can launch an instance of Chrome navigated to your app, or it can attach to a running instance of Chrome. Both modes requires you to be serving your web application from local web server, which is started from either a VS Code task or from your command-line. Using the url parameter you simply tell VS Code which URL to either open or launch in Chrome.

Just like when using the Node debugger, you configure these modes with a .vscode/launch.json file in the root directory of your project. You can create this file manually, or Code will create one for you if you try to run your project, and it doesn't exist yet.

Tip: See recipes for debugging different frameworks here: https://github.com/Microsoft/vscode-recipes

Launch

Two example launch.json configs with 'request': 'launch'. You must specify either file or url to launch Chrome against a local file or a url. If you use a url, set webRoot to the directory that files are served from. This can be either an absolute path or a path using ${workspaceFolder} (the folder open in Code). webRoot is used to resolve urls (like 'http://localhost/app.js') to a file on disk (like /Users/me/project/app.js), so be careful that it's set correctly.

If you want to use a different installation of Chrome, you can also set the runtimeExecutable field with a path to the Chrome app.

Attach

With 'request': 'attach', you must launch Chrome with remote debugging enabled in order for the extension to attach to it. Here's how to do that:

Windows

Right click the Chrome shortcut, and select properties
In the 'target' field, append --remote-debugging-port=9222
Or in a command prompt, execute <path to chrome>/chrome.exe --remote-debugging-port=9222

macOS

In a terminal, execute /Applications/Google Chrome.app/Contents/MacOS/Google Chrome --remote-debugging-port=9222

Linux

In a terminal, launch google-chrome --remote-debugging-port=9222

If you have another instance of Chrome running and don't want to restart it, you can run the new instance under a separate user profile with the --user-data-dir option. Example: --user-data-dir=/tmp/chrome-debug. This is the same as using the userDataDir option in a launch-type config.

Launch Chrome and navigate to your page.

An example launch.json file for an 'attach' config.

Chrome user profile note (`Cannot connect to the target: connect ECONNREFUSED`)

Normally, if Chrome is already running when you start debugging with a launch config, then the new instance won't start in remote debugging mode. So by default, the extension launches Chrome with a separate user profile in a temp folder. Use the userDataDir launch config field to override or disable this. If you are using the runtimeExecutable field, this isn't enabled by default, but you can forcibly enable it with 'userDataDir': true.

If you are using an attach config, make sure you close other running instances of Chrome before launching a new one with --remote-debugging-port. Or, use a new profile with the --user-data-dir flag yourself.

For other troubleshooting tips for this error, see below.

Errors from chrome-error://chromewebdata

If you see errors with a location like chrome-error://chromewebdata/ in the error stack, these errors are not from the extension or from your app - they are usually a sign that Chrome was not able to load your app.

When you see these errors, first check whether Chrome was able to load your app. Does Chrome say 'This site can't be reached' or something similar? You must start your own server to run your app. Double-check that your server is running, and that the url and port are configured correctly.

Other targets

You can also theoretically attach to other targets that support the same Chrome Debugging protocol, such as Electron or Cordova. These aren't officially supported, but should work with basically the same steps. You can use a launch config by setting 'runtimeExecutable' to a program or script to launch, or an attach config to attach to a process that's already running. If Code can't find the target, you can always verify that it is actually available by navigating to http://localhost:<port>/json in a browser. If you get a response with a bunch of JSON, and can find your target page in that JSON, then the target should be available to this extension.

Examples

See our wiki page for some configured example apps: Examples

Other optional launch config fields

trace: When true, the adapter logs its own diagnostic info to a file. The file path will be printed in the Debug Console. This is often useful info to include when filing an issue on GitHub. If you set it to 'verbose', it will also log to the console.
runtimeExecutable: Workspace relative or absolute path to the runtime executable to be used. If not specified, Chrome will be used from the default install location.
runtimeArgs: Optional arguments passed to the runtime executable.
env: Optional dictionary of environment key/value pairs.
cwd: Optional working directory for the runtime executable.
userDataDir: Normally, if Chrome is already running when you start debugging with a launch config, then the new instance won't start in remote debugging mode. So by default, the extension launches Chrome with a separate user profile in a temp folder. Use this option to set a different path to use, or set to false to launch with your default user profile.
url: On a 'launch' config, it will launch Chrome at this URL.
urlFilter: On an 'attach' config, or a 'launch' config with no 'url' set, search for a page with this url and attach to it. It can also contain wildcards, for example, 'localhost:*/app' will match either 'http://localhost:123/app' or 'http://localhost:456/app', but not 'https://stackoverflow.com'.
targetTypes: On an 'attach' config, or a 'launch' config with no 'url' set, set a list of acceptable target types from the default ['page']. For example, if you are attaching to an Electron app, you might want to set this to ['page', 'webview']. A value of null disables filtering by target type.
sourceMaps: By default, the adapter will use sourcemaps and your original sources whenever possible. You can disable this by setting sourceMaps to false.
pathMapping: This property takes a mapping of URL paths to local paths, to give you more flexibility in how URLs are resolved to local files. 'webRoot': '${workspaceFolder}' is just shorthand for a pathMapping like { '/': '${workspaceFolder}' }.
smartStep: Automatically steps over code that doesn't map to source files. Especially useful for debugging with async/await.
disableNetworkCache: If false, the network cache will be NOT disabled. It is disabled by default.
showAsyncStacks: If true, callstacks across async calls (like setTimeout, fetch, resolved Promises, etc) will be shown.
breakOnLoad: Experimental. If true, the debug adapter will attempt to set breakpoints in scripts before they are loaded, so it can hit breakpoints at the beginnings of those scripts. Has a perf impact.
breakOnLoadStrategy: The strategy used for breakOnLoad. Options are 'Instrument' or 'Regex'. Instrument '[tells] Chrome to pause as each script is loaded, resolving sourcemaps and setting breakpoints' Regex '[s]ets breakpoints optimistically in files with the same name as the file in which the breakpoint is set.'

Skip files / Blackboxing / Ignore files

You can use the skipFiles property to ignore/blackbox specific files while debugging. For example, if you set 'skipFiles': ['jquery.js'], then you will skip any file named 'jquery.js' when stepping through your code. You also won't break on exceptions thrown from 'jquery.js'. This works the same as 'blackboxing scripts' in Chrome DevTools.

The supported formats are:

The name of a file (like jquery.js)
The name of a folder, under which to skip all scripts (like node_modules)
A path glob, to skip all scripts that match (like node_modules/react/*.min.js)

Page refreshing

This debugger also enables you to refresh your target by simply hitting the restart button in the debugger UI. Additionally you can map the refresh action to your favorite keyboard shortcut by adding the following key mapping to Key Bindings:

Read more here https://github.com/Microsoft/vscode-chrome-debug-core/issues/91#issuecomment-265027348

Sourcemaps

The debugger uses sourcemaps to let you debug with your original sources, but sometimes the sourcemaps aren't generated properly and overrides are needed. In the config we support sourceMapPathOverrides, a mapping of source paths from the sourcemap, to the locations of these sources on disk. Useful when the sourcemap isn't accurate or can't be fixed in the build process.

The left hand side of the mapping is a pattern that can contain a wildcard, and will be tested against the sourceRoot + sources entry in the source map. If it matches, the source file will be resolved to the path on the right hand side, which should be an absolute path to the source file on disk.

A few mappings are applied by default, corresponding to some common default configs for Webpack and Meteor:

If you set sourceMapPathOverrides in your launch config, that will override these defaults. ${workspaceFolder} and ${webRoot} can be used here. If you aren't sure what the left side should be, you can use the .scripts command (details below). You can also use the trace option to see the contents of the sourcemap, or look at the paths of the sources in Chrome DevTools, or open your .js.map file and check the values manually.

Ionic/gulp-sourcemaps note

Ionic and gulp-sourcemaps output a sourceRoot of '/source/' by default. If you can't fix this via your build config, I suggest this setting:

Usage with remote VS Code extensions

This extension can be used with the VS Code Remote Extensions to debug an app in a local Chrome window. Here's an example workflow using the Remote - SSH extension:

Connect to the SSH remote where your project is located
Launch the development server on the remote
Run the 'Forward Port From Active Host' command to forward the port the server is listening on. For example, if your development server is listening on port 3000, forward port 3000 to the local machine.
Start your 'chrome' launch config
Chrome should start on the local machine, accessing your app via the forwarded port
Debugging works as normally

There are a couple caveats to this workflow:

Since the extension can't currently access the remote disk, sourcemaps can't be read from disk. If sourcemaps are inlined, they will still be used. If possible, they will be downloaded through your webserver.
In a local window, when resolving your script locations with webRoot/pathMapping, the extension does some searching for the correct script. Again, since the extension can't check the remote disk, the extension can't do this searching, so your webRoot/pathMapping must be exactly accurate to resolve the script location.

If you have any other issues, please open an issue.

Troubleshooting

My breakpoints aren't hit. What's wrong?

If your breakpoints aren't hit, it's most likely a sourcemapping issue or because you are having breakpoints in immediately executed code. If you for example have a breakpoint in a render function that runs on page load, sometimes our debugger might not be attached to Chrome before the code has been executed. This means that you will have to refresh the page in Chrome after we have attached from VS Code to hit your breakpoint.

Alternatively, we have an experimental 'break-on-load' configuration option which will make this timing issue more transparent. It landed in https://github.com/microsoft/vscode-chrome-debug-core/pull/241.

If you have a sourcemapping issue, please see https://github.com/Microsoft/vscode-chrome-debug#sourcemaps

Cannot connect to the target: connect ECONNREFUSED 127.0.0.1:9222

This message means that the extension can't attach to Chrome, because Chrome wasn't launched in debug mode. Here are some things to try:

If using an attach type config, ensure that you launched Chrome using --remote-debugging-port=9222. And if there was already a running instance, close it first or see note about --user-data-dir above.
Ensure that the port property matches the port on which Chrome is listening for remote debugging connections. This is 9222 by default. Ensure nothing else is using this port, including your web server. If something else on your computer responds at http://localhost:9222, then set a different port.
If using a launch type config with the userDataDir option explicitly disabled, close other running instances of Chrome - if Chrome is already running, the extension may not be able to attach, when using launch mode. Chrome can even stay running in the background when all its windows are closed, which will interfere - check the taskbar or kill the process if necessary.
If all else fails, try to navigate to http://localhost:<port>/json in a browser when you see this message - if there is no response, then something is wrong upstream of the extension. If there is a page of JSON returned, then ensure that the port in the launch config matches the port in that url.

General things to try if you're having issues:

Ensure webRoot is set correctly if needed
Look at your sourcemap config carefully. A sourcemap has a path to the source files, and this extension uses that path to find the original source files on disk. Check the sourceRoot and sources properties in your sourcemap and make sure that they can be combined with the webRoot property in your launch config to build the correct path to the original source files.
This extension ignores sources that are inlined in the sourcemap - you may have a setup that works in Chrome Dev Tools, but not this extension, because the paths are incorrect, but Chrome Dev Tools are reading the inlined source content.
Check the console for warnings that this extension prints in some cases when it can't attach.
Ensure the code in Chrome matches the code in Code. Chrome may cache an old version.
If your breakpoints bind, but aren't hit, try refreshing the page. If you set a breakpoint in code that runs immediately when the page loads, you won't hit that breakpoint until you refresh the page.
File a bug in this extension's GitHub repo, including the debug adapter log file. Create the log file by setting the 'trace' field in your launch config and reproducing the issue. It will print the path to the log file at the top of the Debug Console. You can drag this file into an issue comment to upload it to GitHub.
If you're using Webpack, we recommend using the 'devtool': 'source-map' option (in your webpack.config.js file) as the others produce lower-fidelity sourcemaps and you may have issues setting breakpoints. See the full list of devtool options for webpack for more information.

The `.scripts` command

This feature is extremely useful for understanding how the extension maps files in your workspace to files running in Chrome. Free can dbc file viewer. You can enter .scripts in the Debug Console to see a listing of all scripts loaded in the runtime, their sourcemap information, and how they are mapped to files on disk. The format is like this:

Example:

If the paths of your source files show as not being resolved correctly here, you may have to change sourceMapPathOverrides or webRoot to help the debugger resolve them to real paths on disk.

If you are wondering what a script is, for example, that 'eval' script, you can also use .scripts to get its contents: .scripts eval://43.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.

Make your life easier, use code actions to do repetitive tasks for you! They can help a lot, just follow the light bulb 💡!

This VS Code extension provides various code actions (quick fixes) when editing code in JavaScript (or TypeScript/Flow). Just note the light bulb at the left and press it to learn how you can transform the code under the cursor.

You might want to reassign the default shortcut for the quick fix menu to Alt+Enter if you are moving from WebStorm. Search for editor.action.quickFix command.

New: React and TypeScript-specific code actions 🚀

Installation

Install through VS Code extensions. Search for JavaScript Booster

Features

Code actions

Conditions
- Flip if-else
- Remove redundant else
- Replace if-else with ?:
- Simplify if-else
- Flip ?:
- Simplify ?:
- Merge nested if statements (new)
Declarations
- Convert var/const to let
- Convert var to const
- Split into multiple declarations
- Split into declaration and initialisation
- Merge declaration and initialisation
Strings
- Replace string with template string
- Replace template string with regular string
- Split string under cursor
- Trim whitespaces inside string (new)
Functions
- Convert shorthand arrow function to statement
- Convert to shorthand arrow function
- Add parens to single arrow function parameter
- Convert function to arrow function
- Convert arrow function to regular function (new)
- Convert function declaration to arrow function (new)
Async
- [on selection] Run selected await statements in parallel with Promise.all
TypeScript
- Convert enum to string-enum (new)
- Convert string-enum to type union (new)
- Convert type union of strings to string-enum (new)
JSX / TSX
- Wrap value with {} (JSX attributes)
- Remove {} from JSX attribute
- Collapse/Expand empty tag
React
- Wrap function into useCallback() hook (new)
- React: Wrap component function with React.forwardRef() (new)
- React: Wrap component function with React.memo() (new)
- React: Convert function to React.FunctionComponent declaration (new)

Extend/Shrink selections

These two commands allow you to successively select blocks of code so that it's easier to select what you want. Just look at the animation, rather than read this text 🤓. Unlike VS Code's embedded commands (editor.action.smartSelect.*), this extension uses an abstract syntax tree under the hood, which provides much more accurate results.

You might want to assign hotkeys for these commands, search for javascriptBooster.extendSelection and javascriptBooster.shrinkSelection. Ctrl+W and Ctrl+Shift+W (⌘W and ⌘⇧W) are used in WebStorm by default.

As this feature is only supported in JavaScript and TypeScript for now, you can configure fallback commands that will be called for other file types instead (VS Code's smartSelect.* by default). They will also be called if the file has fatal syntax errors.

Roadmap

More code actions

Convert if -> switch-case
TS: Change member access (public -> private etc)
TS: Convert alias to interface
TS: Generate missing switch cases for enum
..?

New commands

Duplicate line/selection
Navigate to related files (Hello.jsx -> Hello.scss, Hello.spec.jsx)

Others

Support loading code actions from user workspace: users can create their own, project-related refactorings! 😅

Inspiration

Largely inspired by WebStorm and its variety of code refactorings. The extension uses Babylon to parse the code and then manipulates the abstract syntax tree using jscodeshift.

Contribution

PRs are always welcome. Please refer to the Contribution Guide for tips on how to work with this project. The guide includes basic development workflows like running tests and debugging as well as useful links for creating new code actions.

If you like this project and find it useful, you could also donate to support its development .

Release Notes

14.0.0

In this release: a bunch of new code actions including React and TypeScript; resolve technical debt and do the groundwork for more exciting features!

New code actions
- React: Wrap function into useCallback() hook
- React: Wrap component function with React.forwardRef()
- React: Wrap component function with React.memo()
- React: Convert function to React.FunctionComponent
- TS: Convert enum to string-enum
- TS: Convert string-enum to type union
- TS: Convert type union of strings to string-enum
- Function: Convert arrow function to regular function
- Function: Convert function declaration to arrow function
- Conditions: Merge nested if statements declaration
- String: Trim whitespaces inside string
Fixes
- replace-with-regular-string should not trigger on tagged template strings
- React: convert to regular function now supports React function components
Others
- Add action scoping (e.g. react-only, ts-only)
- Use strict TypeScript in the language server
- Migrate to ESLint
- Switch to Yarn (for selective deps resolution)
- Add log-level, add verbose performance logs

0.12.0

Add new refactoring: Replace ?: with if-else (#19):
Fixed 'Remove redundant else' refactoring not to appear when there is not else statement (#21).
The project now uses Webpack internally to minimize the extension size and improve performance (#22).

0.11.0

Visual Studio Code Javascript Autocomplete

Add new range-based code action: Call await statements in parallel with Promise.All() (#7):
Add new option to adjust formatting for generated code (only needed when a code action generates new code, the formatting of the unaffected code is always preserved). See javascriptBooster.formattingOptions and #10.
Bumped @babel/parser, adds proper Angular support (#13).
Fixed Convert to arrow function refactoring, now works correctly with async functions (#11).
Fixed replace if-else with ?: refactoring, now supports refactoring of pure expressions:

0.10.0

[VSCode API] Switched to using selection parameter passed into provideCodeActions() (Fixes #5)
JSX: Expand empty tag now puts the cursor between the tags when executed.
The myth 2005 telugu. Split string under cursor now puts selection before the second string when executed.
Split string under cursor no longed triggers outside string quotes.
Remove redundant else now supports the case when if branch ends with return statement:
Replace with ternary can now replace conditional return statements:
Added new action: Simplify if-else.
Added new action: Simplify ?:.

0.9.0

Improved language server performance when available code actions are computed.
Fixed Split string literal under the cursor, now works well with a series of concatenations ('foo' + 'bar][baz' => 'foo' + 'bar' + 'baz') and respects escape sequences.
Fixed App parens to arrow function parameter, renamed into Wrap parameter with () to avoid confusion with Add braces to arrow function and now always puts the cursor at the end of the parameter.
Fixed a number of string actions becoming available when under string literals which cannot be transformed (e.g. inside imports, TS enums etc).

0.8.0

Extracted all AST-related operations into a Language Server. Massively improves UI responsiveness, particularly when working with large files. 🔥
Added new code action: Split string literal under the cursor.
Fixed Split into declaration and initialization to work when inside a function/arrow expression.