React is a popular JavaScript library developed by Facebook for building web application user interfaces. The Visual Studio Code editor supports React.js IntelliSense and code navigation out of the box.
Welcome to React
We'll be using the create-react-appgenerator for this tutorial. To use the generator as well as run the React application server, you'll need Node.js JavaScript runtime and npm (Node.js package manager) installed. npm is included with Node.js which you can download and install from Node.js downloads.
Tip: To test that you have Node.js and npm correctly installed on your machine, you can type node --version and npm --version in a terminal or command prompt.
You can now create a new React application by typing:
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where my-app is the name of the folder for your application. This may take a few minutes to create the React application and install its dependencies.
Note: If you've previously installed create-react-app globally via npm install -g create-react-app, we recommend you uninstall the package using npm uninstall -g create-react-app to ensure that npx always uses the latest version.
Let's quickly run our React application by navigating to the new folder and typing npm start to start the web server and open the application in a browser:
You should see the React logo and a link to 'Learn React' on http://localhost:3000 in your browser. We'll leave the web server running while we look at the application with VS Code.
To open your React application in VS Code, open another terminal or command prompt window, navigate to the my-app folder and type code .:
Markdown preview
In the File Explorer, one file you'll see is the application README.md Markdown file. This has lots of great information about the application and React in general. A nice way to review the README is by using the VS Code Markdown Preview. You can open the preview in either the current editor group (Markdown: Open Preview⇧⌘V (Windows, Linux Ctrl+Shift+V)) or in a new editor group to the side (Markdown: Open Preview to the Side⌘K V (Windows, Linux Ctrl+K V)). You'll get nice formatting, hyperlink navigation to headers, and syntax highlighting in code blocks.
Syntax highlighting and bracket matching
Now expand the src folder and select the index.js file. You'll notice that VS Code has syntax highlighting for the various source code elements and, if you put the cursor on a parenthesis, the matching bracket is also selected.
IntelliSense
As you start typing in index.js, you'll see smart suggestions or completions.
After you select a suggestion and type ., you see the types and methods on the object through IntelliSense.
VS Code uses the TypeScript language service for its JavaScript code intelligence and it has a feature called Automatic Type Acquisition (ATA). ATA pulls down the npm Type Declaration files (*.d.ts) for the npm modules referenced in the package.json.
If you select a method, you'll also get parameter help:
Go to Definition, Peek definition
Through the TypeScript language service, VS Code can also provide type definition information in the editor through Go to Definition (F12) or Peek Definition (⌥F12 (Windows Alt+F12, Linux Ctrl+Shift+F10)). Put the cursor over the App, right click and select Peek Definition. A Peek window will open showing the App definition from App.js.
Press Escape to close the Peek window.
Hello World!
Let's update the sample application to 'Hello World!'. Create a new H1 header with 'Hello, world!' and replace the <App /> tag in ReactDOM.render with element.
Once you save the index.js file, the running instance of the server will update the web page and you'll see 'Hello World!' when you refresh your browser.
Tip: VS Code supports Auto Save, which by default saves your files after a delay. Check the Auto Save option in the File menu to turn on Auto Save or directly configure the files.autoSave user setting.
Debugging React
Visual Studio Code Debug Node
To debug the client side React code, we'll need to install the Debugger for Chrome extension.
Note: This tutorial assumes you have the Chrome browser installed. There are also debugger extensions for the Edge and Firefox browsers.
Open the Extensions view (⇧⌘X (Windows, Linux Ctrl+Shift+X)) and type 'chrome' in the search box. You'll see several extensions which reference Chrome.
Press the Install button for Debugger for Chrome.
Set a breakpoint
To set a breakpoint in index.js, click on the gutter to the left of the line numbers. This will set a breakpoint which will be visible as a red circle.
Configure the Chrome debugger
We need to initially configure the debugger. To do so, go to the Run view (⇧⌘D (Windows, Linux Ctrl+Shift+D)) and click create a launch.json file to customize Run and Debug. Choose Chrome from the Select Environment dropdown list. This will create a launch.json file in a new .vscode folder in your project which includes a configuration to launch the website.
We need to make one change for our example: change the port of the url from 8080 to 3000. Your launch.json should look like this:
Ensure that your development server is running (npm start). Then press F5 or the green arrow to launch the debugger and open a new browser instance. The source code where the breakpoint is set runs on startup before the debugger was attached, so we won't hit the breakpoint until we refresh the web page. Refresh the page and you should hit your breakpoint.
You can step through your source code (F10), inspect variables such as element, and see the call stack of the client side React application.
The Debugger for Chrome extension README has lots of information on other configurations, working with sourcemaps, and troubleshooting. You can review it directly within VS Code from the Extensions view by clicking on the extension item and opening the Details view.
Live editing and debugging
If you are using webpack together with your React app, you can have a more efficient workflow by taking advantage of webpack's HMR mechanism which enables you to have live editing and debugging directly from VS Code. You can learn more in this Live edit and debug your React apps directly from VS Code blog post and the webpack Hot Module Replacement documentation.
Linting
Linters analyze your source code and can warn you about potential problems before you run your application. The JavaScript language services included with VS Code has syntax error checking support by default, which you can see in action in the Problems panel (View > Problems⇧⌘M (Windows, Linux Ctrl+Shift+M)).
Try making a small error in your React source code and you'll see a red squiggle and an error in the Problems panel.
Linters can provide more sophisticated analysis, enforcing coding conventions and detecting anti-patterns. A popular JavaScript linter is ESLint. ESLint, when combined with the ESLint VS Code extension, provides a great in-product linting experience.
First, install the ESLint command-line tool:
Then install the ESLint extension by going to the Extensions view and typing 'eslint'.
Once the ESLint extension is installed and VS Code reloaded, you'll want to create an ESLint configuration file, .eslintrc.js. You can create one using the extension's ESLint: Create ESLint configuration command from the Command Palette (⇧⌘P (Windows, Linux Ctrl+Shift+P)).
The command will prompt you to answer a series of questions in the Terminal panel. Take the defaults, and it will create a .eslintrc.js file in your project root that looks something like this:
ESLint will now analyze open files and shows a warning in index.js about 'App' being defined but never used.
You can modify the ESLint rules in the .eslintrc.js file.
Let's add an error rule for extra semi-colons:
Now when you mistakenly have multiple semicolons on a line, you'll see an error (red squiggle) in the editor and error entry in the Problems panel.
Popular Starter Kits
In this tutorial, we used the create-react-app generator to create a simple React application. There are lots of great samples and starter kits available to help build your first React application.
VS Code React Sample
This is a sample React application used for a demo at the 2016 //Build conference. The sample creates a simple TODO application and includes the source code for a Node.js Express server. It also shows how to use the Babel ES6 transpiler and then use webpack to bundle the site assets.
TypeScript React
If you're curious about TypeScript and React, you can also create a TypeScript version of the create-react-app application by specifying that you want to use the TypeScript template:
See the details at Adding TypeScript on the Create React App site.
Angular
Angular is another popular web framework. If you'd like to see an example of Angular working with VS Code, check out the Chrome Debugging with Angular CLI recipe. It will walk you through creating an Angular application and configuring the launch.json file for the Debugger for Chrome extension.
Visual Studio Node Js Debugging
Common questions
Can I get IntelliSense within declarative JSX?
Yes. For example, if you open the create-react-app project's App.js file, you can see IntelliSense within the React JSX in the render() method.
The NuGet Package Manager UI in Visual Studio on Windows allows you to easily install, uninstall, and update NuGet packages in projects and solutions. For the experience in Visual Studio for Mac, see Including a NuGet package in your project. The Package Manager UI is not included with Visual Studio Code.
Note
If you're missing the NuGet Package Manager in Visual Studio 2015, check Tools > Extensions and Updates... and search for the NuGet Package Manager extension. If you're unable to use the extensions installer in Visual Studio, download the extension directly from https://dist.nuget.org/index.html.
Starting in Visual Studio 2017, NuGet and the NuGet Package Manager are automatically installed with any .NET-related workloads. Install it individually by selecting the Individual components > Code tools > NuGet package manager option in the Visual Studio installer.
Find and install a package
In Solution Explorer, right-click either References or a project and select Manage NuGet Packages....
The Browse tab displays packages by popularity from the currently selected source (see package sources). Search for a specific package using the search box on the upper left. Select a package from the list to display its information, which also enables the Install button along with a version-selection drop-down.
Select the desired version from the drop-down and select Install. Visual Studio installs the package and its dependencies into the project. You may be asked to accept license terms. When installation is complete, the added packages appear on the Installed tab. Packages are also listed in the References node of Solution Explorer, indicating that you can refer to them in the project with
usingstatements.
Tip
To include prerelease versions in the search, and to make prerelease versions available in the version drop-down, select the Include prerelease option.
Note
NuGet has two formats in which a project may use packages: PackageReference and packages.config. The default can be set in Visual Studio's options window.
Uninstall a package
In Solution Explorer, right-click either References or the desired project, and select Manage NuGet Packages....
Select the Installed tab.
Select the package to uninstall (using search to filter the list if necessary) and select Uninstall.
Note that the Include prerelease and Package source controls have no effect when uninstalling packages.
Update a package
In Solution Explorer, right-click either References or the desired project, and select Manage NuGet Packages.... (In web site projects, right-click the Bin folder.)
Select the Updates tab to see packages that have available updates from the selected package sources. Select Include prerelease to include prerelease packages in the update list.
Select the package to update, select the desired version from the drop-down on the right, and select Update.
For some packages, the Update button is disabled and a message appears saying that it's 'Implicitly referenced by an SDK' (or 'AutoReferenced'). This message indicates that the package is part of a larger framework or SDK and should not be updated independently. (Such packages are internally marked with
<IsImplicitlyDefined>True</IsImplicitlyDefined>.) For example,Microsoft.NETCore.Appis part of the .NET Core SDK, and the package version is not the same as the version of the runtime framework used by the application. You need to update your .NET Core installation to get new versions of the ASP.NET Core and .NET Core runtime. See this document for more details on .NET Core metapackages and versioning. This applies to the following commonly used packages:- Microsoft.AspNetCore.All
- Microsoft.AspNetCore.App
- Microsoft.NETCore.App
- NETStandard.Library
To update multiple packages to their newest versions, select them in the list and select the Update button above the list.
You can also update an individual package from the Installed tab. In this case, the details for the package include a version selector (subject to the Include prerelease option) and an Update button.
Manage packages for the solution
Managing packages for a solution is a convenient means to work with multiple projects simultaneously.
Select the Tools > NuGet Package Manager > Manage NuGet Packages for Solution... menu command, or right-click the solution and select Manage NuGet Packages...:
When managing packages for the solution, the UI lets you select the projects that are affected by the operations:
Consolidate tab
Developers typically consider it bad practice to use different versions of the same NuGet package across different projects in the same solution. When you choose to manage packages for a solution, the Package Manager UI provides a Consolidate tab on which you can easily see where packages with distinct version numbers are used by different projects in the solution:
In this example, the ClassLibrary1 project is using EntityFramework 6.2.0, whereas ConsoleApp1 is using EntityFramework 6.1.0. To consolidate package versions, do the following:
- Select the projects to update in the project list.
- Select the version to use in all those projects in the Version control, such as EntityFramework 6.2.0.
- Select the Install button.
The Package Manager installs the selected package version into all selected projects, after which the package no longer appears on the Consolidate tab.
Package sources
To change the source from which Visual Studio obtains packages, select one from the source selector:
Visual Studio Node.js
To manage package sources:
Select the Settings icon in the Package Manager UI outlined below or use the Tools > Options command and scroll to NuGet Package Manager:
Select the Package Sources node:
To add a source, select +, edit the name, enter the URL or path in the Source control, and select Update. The source now appears in the selector drop-down.
To change a package source, select it, make edits in the Name and Source boxes, and select Update.
To disable a package source, clear the box to the left of the name in the list.
To remove a package source, select it and then select the X button.
Using the up and down arrow buttons does not change the priority order of the package sources. Visual Studio ignores the order of package sources, using the package from whichever source is first to respond to requests. For more information, see Package restore.
Tip
If a package source reappears after deleting it, it may be listed in a computer-level or user-level NuGet.Config files. See Common NuGet configurations for the location of these files, then remove the source by editing the files manually or using the nuget sources command.
Package manager Options control
When a package is selected, the Package Manager UI displays a small, expandable Options control below the version selector (shown here both collapsed and expanded). Note that for some project types, only the Show preview window option is provided.
The following sections explain these options.
Show preview window
When selected, a modal window displays which the dependencies of a chosen package before the package is installed:
Install and Update Options
(Not available for all project types.)
Dependency behavior configures how NuGet decides which versions of dependent packages to install:
- Ignore dependencies skips installing any dependencies, which typically breaks the package being installed.
- Lowest [Default] installs the dependency with the minimal version number that meets the requirements of the primary chosen package.
- Highest Patch installs the version with the same major and minor version numbers, but the highest patch number. For example, if version 1.2.2 is specified then the highest version that starts with 1.2 will be installed
- Highest Minor installs the version with the same major version number but the highest minor number and patch number. If version 1.2.2 is specified, then the highest version that starts with 1 will be installed
- Highest installs the highest available version of the package.
File conflict action specifies how NuGet should handle packages that already exist in the project or local machine:
- Prompt instructs NuGet to ask whether to keep or overwrite existing packages.
- Ignore All instructs NuGet to skip overwriting any existing packages.
- Overwrite All instructs NuGet to overwrite any existing packages.
Uninstall Options
(Not available for all project types.)
Remove dependencies: when selected, removes any dependent packages if they're not referenced elsewhere in the project.
Force uninstall even if there are dependencies on it: when selected, uninstalls a package even if it's still being referenced in the project. This is typically used in combination with Remove dependencies to remove a package and whatever dependencies it installed. Using this option may, however, lead to broken references in the project. In such cases, you may need to reinstall those other packages.