Web & code · .js
What Is a JS File?
A .js file is a JavaScript program file, used by websites and apps.
- Extension
- .js
- Full name
- JavaScript file
- Type
- Web & code
- MIME type
- text/javascript
Free JS Tools
These run in your browser. Your JS files are never uploaded.
About JS Files
JS files contain JavaScript, the programming language of the web. Browsers run JavaScript to make pages interactive, and Node.js runs it on servers and in development tools. A .js file is plain text you can read in any editor. On Windows, double-clicking a .js file runs it with Windows Script Host rather than opening it, which malware has exploited, so don't open .js email attachments.
How to Open a JS File
- Any device
- Open it in a text editor or VS Code to read it.
- Windows
- Right-click and choose Open with, then Notepad. Don't double-click unknown JS files.
JS File Questions
Is a .js email attachment dangerous?
Yes, very likely. On Windows, double-clicking runs it. Delete unexpected .js attachments.
How do I run a JS file?
Install Node.js and run node file.js, or include it in a web page with a script tag.