Using React in Visual Studio Code

React is a popular JavaScript library developed by Facebook for building 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 thecreate-react-appgenerator for this tutorial. To use the generator as well as run the React application server, you'll needNode.js JavaScript runtime andnpm (Node.js package manager) installed. npm is included with Node.js which you can download and install fromNode.js downloads.

Tip: To test that you have Node.js and npm correctly installed on your machine, you can typenode --version andnpm --version in a terminal or command prompt.

You can now create a new React application by typing:

npx create-react-app my-app

wheremy-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 installedcreate-react-app globally vianpm install -g create-react-app, we recommend you uninstall the package usingnpm 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 typingnpm start to start the web server and open the application in a browser:

cd my-appnpm start

You should see the React logo and a link to "Learn React" onhttp://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 themy-app folder and typecode .:

cd my-appcode .

Markdown preview

In the File Explorer, one file you'll see is the applicationREADME.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 CodeMarkdown Preview. You can open the preview in either the current editor group (Markdown: Open Preview⇧⌘V (Windows, LinuxCtrl+Shift+V)) or in a new editor group to the side (Markdown: Open Preview to the Side⌘K V (Windows, LinuxCtrl+K V)). You'll get nice formatting, hyperlink navigation to headers, and syntax highlighting in code blocks.

Syntax highlighting and bracket matching

Now expand thesrc folder and select theindex.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 inindex.js, you'll see smart suggestions or completions.

After you select a suggestion and type., you see the types and methods on the object throughIntelliSense.

VS Code uses the TypeScript language service for its JavaScript code intelligence and it has a feature calledAutomatic Type Acquisition (ATA). ATA pulls down the npm Type Declaration files (*.d.ts) for the npm modules referenced in thepackage.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 throughGo to Definition (F12) orPeek Definition (⌥F12 (WindowsAlt+F12, LinuxCtrl+Shift+F10)). Put the cursor over theApp, right click and selectPeek Definition. APeek window will open showing theApp definition fromApp.js.

PressEscape to close the Peek window.

Hello World

Let's update the sample application to "Hello World!". Create a component insideindex.js calledHelloWorld that contains a H1 header with "Hello, world!" and replace the<App /> tag inroot.render with<HelloWorld />.

import React from 'react';import ReactDOM from 'react-dom/client';import './index.css';import App from './App';import reportWebVitals from './reportWebVitals';function HelloWorld() {  return <h1 className="greeting">Hello, world!</h1>;}const root =ReactDOM.createRoot(document.getElementById('root'));root.render(  <React.StrictMode>    <HelloWorld />  </React.StrictMode>);// If you want to start measuring performance in your app, pass a function// to log results (for example: reportWebVitals(console.log))// or send to an analytics endpoint. Learn more: https://bit.ly/CRA-vitalsreportWebVitals();

Once you save theindex.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 theAuto Save option in theFile menu to turn on Auto Save or directly configure thefiles.autoSave usersetting.

Debugging React

To debug the client side React code, we'll use the built-in JavaScript debugger.

Note: This tutorial assumes you have the Edge browser installed. If you want to debug using Chrome, replace the launchtype withchrome. There is also a debugger for theFirefox browser.

Set a breakpoint

To set a breakpoint inindex.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 debugger

We need to initially configure thedebugger. To do so, go to theRun and Debug view (⇧⌘D (Windows, LinuxCtrl+Shift+D)) and select thecreate a launch.json file link to create alaunch.json debugger configuration file. ChooseWeb App (Edge) from theSelect debugger dropdown list. This will create alaunch.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 theurl from8080 to3000. Yourlaunch.json should look like this:

{  "version":"0.2.0",  "configurations": [    {      "type":"msedge",      "request":"launch",      "name":"Launch Edge against localhost",      "url":"http://localhost:3000",      "webRoot":"${workspaceFolder}"    }  ]}

Ensure that your development server is running (npm start). Then pressF5 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 asHelloWorld, and see the call stack of the client side React application.

For more information about the debugger and its available options, check out our documentation onbrowser debugging.

Live editing and debugging

If you are usingwebpack 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 thisLive edit and debug your React apps directly from VS Code blog post and thewebpack 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 theProblems panel (View >Problems⇧⌘M (Windows, LinuxCtrl+Shift+M)).

Try making a small error in your React source code and you'll see a red squiggle and an error in theProblems panel.

Linters can provide more sophisticated analysis, enforcing coding conventions and detecting anti-patterns. A popular JavaScript linter isESLint. ESLint, when combined with the ESLint VS Codeextension, provides a great in-product linting experience.

First, install the ESLint command-line tool:

npm install -g eslint

Then install the ESLint extension by going to theExtensions 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'sESLint: Create ESLint configuration command from theCommand Palette (⇧⌘P (Windows, LinuxCtrl+Shift+P)).

The command will prompt you to answer a series of questions in theTerminal panel. Take the defaults, and it will create a.eslintrc.js file in your project root that looks something like this:

module.exports = {  env: {    browser: true,    es2020: true  },  extends: ['eslint:recommended','plugin:react/recommended'],  parserOptions: {    ecmaFeatures: {      jsx: true    },    ecmaVersion: 11,    sourceType: 'module'  },  plugins: ['react'],  rules: {}};

ESLint will now analyze open files and shows a warning inindex.js about 'App' being defined but never used.

You can modify the ESLintrules in the.eslintrc.js file.

Let's add an error rule for extra semi-colons:

 "rules": {        "no-extra-semi":"error"    }

Now when you mistakenly have multiple semicolons on a line, you'll see an error (red squiggle) in the editor and error entry in theProblems panel.

Popular Starter Kits

In this tutorial, we used thecreate-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 asample React application, which creates a simple TODO application and includes the source code for a Node.jsExpress server. It also shows how to use theBabel ES6 transpiler and then usewebpack to bundle the site assets.

TypeScript React

If you're curious about TypeScript and React, you can also create a TypeScript version of thecreate-react-app application by specifying that you want to use the TypeScript template:

npx create-react-app my-app --template typescript

See the details atAdding TypeScript on theCreate 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 theDebugging with Angular CLI recipe. It will walk you through creating an Angular application and configuring thelaunch.json file for the JavaScript debugger.

Common questions

Can I get IntelliSense within declarative JSX?

Yes. For example, if you open thecreate-react-app project'sApp.js file, you can see IntelliSense within the React JSX in therender() method.