JavaScript files are normally found in web pages where your web page interprets instructions and executes them. JavaScript in a web page is safe as the browser limits the fish bowl where it lives to a single web page. JavaScript let loose on a Windows machine is an entirely different matter. Microsoft is to blame for hiding the file type portion of the file names by hiding them by default. Changing this default behavior, makes a Windows computer safer. Perhaps the safest thing to do with JavaScript files is to open them in Notepad.”]
Source: https://www.computerworld.com/article/3090146/blocking-javascript-can-stop-some-windows-malware.html