How to run JavaScript in Visual Studio Code?

In this article, we will learn how to run JavaScript in Visual Studio Code (VSCode) and how to make the most out of the features provided by this popular code editor.

While many developers are already familiar with VSCode, it is essential to know how it can improve your JavaScript development experience, whether you are working with Vanilla JS or popular frameworks like React.

VSCode has built-in support for JavaScript, providing features such as syntax highlighting, code completion, and debugging. However, it does not include a native way to run JavaScript code.

In this tutorial, we will walk through how to configure VSCode to run and debug JavaScript efficiently, regardless of whether you are using Vanilla JS or a framework like React.

Prerequisites

Before we begin, ensure that you have the following installed on your system:

• Visual Studio Code
• Node.js

If you don't have these installed, don't worry – we will cover the installation process in the next section.

Installation and Configuration

1. Installing Visual Studio Code

To install Visual Studio Code, head to the official website at and download the appropriate version for your operating system. Follow the installation prompts and complete the setup.

2. Installing Node.js

Node.js is an open-source, cross-platform runtime environment that allows you to run JavaScript outside of a web browser.

To install Node.js, visit the official website and download the recommended version for your operating system. Run the installer and follow the on-screen instructions.

3. Installing Code Runner Extension

Code Runner is a popular extension for VSCode that allows you to run code snippets or code files in multiple programming languages, including JavaScript. To install Code Runner, follow these steps:

• Open Visual Studio Code.

• Click on the Extensions view icon on the Sidebar or press Ctrl+Shift+X.

• In the Extensions search bar, type "Code Runner" and press Enter.

• Find the Code Runner extension by Jun Han and click the Install button(or install by the above link).

• Once the installation is complete, you will see a "Run Code" button in the top-right corner of the VSCode window.

Running JavaScript in Visual Studio Code

1. Creating a JavaScript File

To create a new JavaScript file in Visual Studio Code, follow these steps:

• Open Visual Studio Code.

• Click on the File menu and select New File or press Ctrl+N.

• Save the file with a .js extension, e.g., example.js, by clicking on the File menu and selecting Save As or pressing Ctrl+Shift+S. Now you can write your JavaScript code in the newly created file.

2. Running the JavaScript File

Once you have written your JavaScript code, you can run it using the Code Runner extension. To do this, follow these steps:

• Open the JavaScript file in Visual Studio Code.

• Click the Run Code button in the top-right corner of the window or press Ctrl+Alt+N.

• The output of your code will be displayed in the Output panel at the bottom of the window.

After completing the previous steps, you can use the following sample JavaScript file to test the Code Runner extension in your VSCode environment:

const greet = (name) => {
  console.log(`Hello, ${name}!`);
};

const sum = (a, b) => {
  return a + b;
};

const name = 'John Doe';
greet(name);

const result = sum(3, 4);
console.log(`The sum of 3 and 4 is: ${result}`);

Save this code as example.js in your project directory and follow the steps mentioned earlier to run it using the Code Runner extension.

Debugging JavaScript in Visual Studio Code

Visual Studio Code also provides a powerful debugger for JavaScript, which can be very useful for finding and fixing errors in your code. In this section, we will cover how to set up and use the debugger for JavaScript in Visual Studio Code.

1. Setting up the Debugger

To set up the debugger for your JavaScript project, follow these steps:

• Open your JavaScript file in Visual Studio Code.

• Click on the Run view icon in the Sidebar or press Ctrl+Shift+D.

• In the Run view, click on the "create a launch.json file" link.

• In the "Select Environment" dropdown menu, choose "Node.js".

• Save the generated launch.json file in the .vscode folder of your project.

This will create a new configuration file called launch.json with the necessary settings for debugging JavaScript in Visual Studio Code using Node.js.

2. Adding Breakpoints and Inspecting Variables

Now that the debugger is set up, you can add breakpoints to your code to pause its execution and inspect the values of variables at specific points.

To add a breakpoint, follow these steps:

• Open your JavaScript file in Visual Studio Code.

• Click in the left margin next to the line number where you want to add a breakpoint. A red dot will appear, indicating the breakpoint.

To start debugging, follow these steps:

1. Click on the Run view icon in the Sidebar or press Ctrl+Shift+D.

2. Click the green "Run" button or press F5.

The debugger will start, and your code will execute until it reaches the breakpoint. At this point, the debugger will pause, and you can inspect the values of variables in the "Variables" section of the Run view.

You can also use the debugging controls in the top of the window to step through your code, resume execution, or stop debugging. The most commonly used debugging controls are:

• Step Over (F10): Executes the current line of code and moves to the next one.

• Step Into (F11): Steps into the function called on the current line of code.

• Step Out (Shift+F11): Steps out of the current function and back to the calling line of code.

• Continue (F5): Resumes execution of the code until the next breakpoint or until the program ends.

• Stop (Shift+F5): Stops the debugger and terminates the running process.

Run and debug React

Now, let's see how to run and debug JavaScript frameworks like React in VSCode. We will use Vite, a fast development and build tool, to set up a basic React application.

1. Setting up a React Application with Vite

To create a new React application using Vite, first, ensure that you have Node.js and npm installed on your system. Then, open your terminal or command prompt and run the following commands:

npm init @vitejs/app my-react-app --template react
cd my-react-app
code .

This will create a new React app named "my-react-app" using the React template, change your working directory to the newly created app, and open the app in Visual Studio Code.

2. Running and Debugging the React Application

Vite sets up the necessary scripts for running and debugging the application. To run the application, open the terminal in VSCode (View > Terminal) and execute the following command:

npm install
npm run dev

This will install the required dependencies and start the development server. Your React app should now be accessible at http://localhost:3000.

To debug the React app, set breakpoints in your code as described earlier in this article. Then, go to the Run view Ctrl+Shift+D and click the green Run button or press F5. The application will open in a new browser window with the debugger attached.

Note: If you encounter any issues with the debugger not attaching, you may need to install the "Debugger for Chrome" or "Debugger for Firefox" extension, depending on the browser you are using.

Now you should be able to run and debug JavaScript in Visual Studio Code, whether you are working with Vanilla JS or a JavaScript framework like React. Armed with this knowledge, you can develop your projects more efficiently and with fewer errors.

Conclusion

In this article, we explored how to run and debug JavaScript in Visual Studio Code, covering the installation and configuration of Visual Studio Code, Node.js, and the Code Runner extension. We demonstrated how to create, run, and debug JavaScript files in Visual Studio Code, both for Vanilla JS and popular frameworks like React using Vite.

By following this tutorial, you should now be able to run and debug JavaScript code efficiently in Visual Studio Code, enabling a more streamlined development process for your projects. Regardless of whether you are working with Vanilla JS or modern frameworks like React, this knowledge will empower you to develop faster and with greater accuracy, enhancing your overall coding experience.

Happy coding!