How to run .js file in the Terminal

JavaScript is a language used in most web projects as a third layer of many web pages, making them more interactive and dynamic. Originally used for creating interactive web page elements, it has grown into a bona fide language used in various spheres. This language is not only used for web development; it is also used in mobile application development, game development, and server-side programming using the Node.js framework.

JavaScript apparently remains popular with its stunning simplicity and versatility making it a “must-know” language for developers interested in creating good user experiences and interfaces. In this blog, we will be briefing you on “How to run js file in the terminal” and the blockers you might face while working on this.

Why running JavaScript in the terminal can be useful

Interacting with JavaScript on the command line can be extremely helpful, especially for front-end development as well as back-end using Node.js. Due to the versatility of terminal and JS shell, developers are able to execute code snippets and work through the logic and function checks without the mess of a full web environment.

It is in this aspect that JavaScript (with Node.js) forms the backbone of backend development to provide services such as data computation, request processing, and management of databases. Using JavaScript in terminals also facilitates speed in developing and testing the frames, and thus highly reduces the cycle time spent in checking for errors that are common during the development process.

Prerequisites to run a JavaScript

You cannot run JavaScript outside a browser, so you need the Node.js environment that allows running JavaScript on servers or typing commands directly into terminals. Node.js therefore enables developers to write server-side code and create robust applications with JavaScript other than web engagements.

Node.js Installation

1. Download Node.js

Visit the Node.js website which is the global official website. Select the version that corresponds to your operating system (Windows, MacOSX, or Linux). Generally a stable  LTS (Long-Term Support) version is advised as the most appropriate because of the stability.

2. Install Node.js:

Launch the downloaded installer and proceed with the instructions on the screen.

Don’t forget to select the check box to install Node Package Manager (npm), it is a part of Node.js used for managing packages for JavaScript.

3. Verify the Installation:

Start the terminal or command prompt of your computer and to ensure that Node.js and npm were installed check the version of Node.js by executing the following command.

node -v or npm -v

The above two commands should normally return the version number, this indicates that the installation has undergone well.

Once Node.js is installed as mentioned above, it means you can immediately begin executing JavaScript code on the terminal.

Setting Up the Javascript File

Before we explain how to run JavaScript file in Node.js, let’s create a simple JavaScript file and test it.

1. Create a JavaScript File:

As soon as you are done typing, get your code or text editor ready. In a new tab open a new unnamed file and then change its name to hello.js.

2. Add Code to the File:

Inside hello.js, type the following code:

console.log("Hello, this is a new JavaScript file!");

In the above line of code, console.log will output ‘Hello, this is a new JavaScript file!’ to the terminal.

3. Save the file:

Once hello.js is all configured, you will now be able to write JavaScript in the terminal using the Node run js file. This method gives everyday man a simple way of testing whether Node.js is well installed on his/her system.

Running the JavaScript File in the Terminal

Once you have your JavaScript file created, you can then execute the file using a javascript compiler through the terminal in Node.js.

1. Navigate to the File Location:

Launch your terminal or command prompt in your computer system. To get to the directory where your hello.js is located use the cd command.

cd path/to/your/file

Here change path/to/your/file to the folder location of hello.js

2. Executing the File with Node.js:

Once in the correct directory, run the following command to execute your JavaScript file:

node hello.js

This command tells Node.js to run a file called hello.js.

3. See the Output:

After running the command, it compiles run javascript and you should see the output-

Hello, this is a new JavaScript file!

Troubleshooting Common Issues

When using JavaScript with Node.js, there are several kinds of mistakes that may happen. Here’s how to troubleshoot them:

Error: command not found

• Cause: This means that Node.js is not installed or the terminal does not recognize Node.js most of the time.
• Solution: Check Node.js installation by entering node -v. If it’s not, then, you follow the installation steps outlined above. If Node.js is installed and is still not recognized, try closing your terminal and reopening it.

Error: SyntaxError or ReferenceError

• Cause: These mistakes are normally made as a result of carelessness or perhaps typing mistakes when creating your coding tasks.
• Solution: Look through the code in your JavaScript file twice in order to make sure there are no typographical errors or extra/missing space. For example, make sure that console.log is spelled appropriately and that all parentheses are rightly curved.

Error: Node.js Version Compatibility

• Cause: It is also possible that some features go well with a particular Node.js version.
• Solution: Use node -v to ascertain the version then ensure you download the newer Node.js by visiting the Node.js homepage.

No Output in Terminal

• Cause: This may happen if your file does not contain console.log or any output code at all.
• Solution: Check the hello.js console.log directive and make sure you’re in the right directory.

That’s all you can do to solve most problems and perform JavaScript with Node.js in the terminal.

Conclusion

This blog guides you on how to run js file outside a web browser with the help of Node.js. You understood how to download Node.js, create a JavaScript file, open a terminal, and how to run JavaScript in terminal.

Wishing you all the best —Happy coding! 🚀