.JS File Extension

JavaScript File

Developer N/A
Popularity
4.0  |  308 Votes
 
NEW: Open your .JS file online with File Helper.View Online

What is a JS file?

A JS file is a plain text file that contains JavaScript code. It is used to execute JavaScript instructions in a webpage. JS files may include functions that open and close windows, validate form fields, enable rollover images, or create dropdown menus.

More Information

Screenshot of a .js file in Microsoft Visual Studio Code
JS file open in Microsoft Visual Studio Code

Web developers use JavaScript to add dynamic and interactive elements to webpages. One of the ways developers can add JavaScript functions to a webpage is by importing them using a JS file.

Developers usually import JS files in the <head> or <body> sections of a webpage's HTML, as shown below:

<head> <script type="text/javascript" src="FileInfo.comExample.js"></script> </head>

JS files often contain standard or site-wide functions that a developer wants to include on each of a site's webpages. Storing the functions in a single, importable JS file makes them easier to maintain and troubleshoot.

How to open a JS file

You can open and edit a JS file in any text or source code editor. Source code editors, such as Microsoft Visual Studio Code and GitHub Atom contain helpful syntax-highlighting and code-editing tools that make reading and editing JS files easier.

Programs that open JS files

JScript Executable Script

Developer Microsoft
Popularity
3.7  |  92 Votes
 

A JS file may also be a script written in JScript, a Microsoft implementation of JavaScript designed to run on Windows-based systems. JS files contain executable code that automates tasks primarily in web development or Windows applications. For example, users may embed JS scripts in .HTML webpages for form validation or automate tasks in Windows to manage files.

More Information

Microsoft released JScript in 1996 to be compatible with the Microsoft software ecosystem, most notably, the Internet Explorer browser. It is similar to JavaScript but bears various deficiencies, including security issues. Microsoft eventually discontinued support for JScript in favor of JavaScript (also saved as .JS files), which offers broader cross-platform support.

How to open a JS file

You can open and edit JS files with any text or source code editor, including Microsoft Notepad, Apple TextEdit, and Microsoft Visual Studio Code.

Programs that open JS files

Windows
Windows-based script host (Wscript.exe)
Included with OS

Verified by FileInfo.com

The FileInfo.com team has independently researched all file formats and software programs listed on this page. Our goal is 100% accuracy and we only publish information about file types that we have verified.

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