Is Javascript for scripting browsers?

Question

In other words, if you try to use it for scripting something other than a browser, is it not likely to work?

For example, a command line shell script uses its own scripting language. Javascript wouldn't work there?

Answer 1

No. Every Windows installation since Win2k (maybe even NT) has JavaScript available for administrative scripting purposes. It's called JScript, by Microsoft, but it is JavaScript with built-in objects that read and modify user and system settings. Read more at:

https://msdn.microsoft.com/en-us/library/hbxc2t98(v=vs.84).aspx



JScript runs within what's called the Windows Script Host (WSH) and you have a choice of languages. JS and VBS (based on Visual Basic) are standard, and third party languages may be added. The examples in the above tutorial have how-to code for both JS and VBS.



This is an older version of JavaScript, by the way, based on ECMA version 3. Modern browsers are using version 5 or later.



More recently, projects like Node.JS have adapted Chrome's open-source JavaScript engine to run standalone. This is finding increasing use in server-side scripting for web applications, and can be used just as languages like Python and Perl are for general-purpose scripting.

https://nodejs.org/en/



It's open source, running on most "real" operating systems, (Windows, Mac, Linux, Unix, SunOS, AIX, etc.) but maybe not mobile platforms. Chrome and IOS, lacking a command line, have no need for command line scripting and presumably have their own admin scripting solutions.



Mozilla SpiderMonkey is also available, using Firefox's open-source JS engine:

https://developer.mozilla.org/en-US/docs/Mozilla/Projects/SpiderMonkey



...and MDN lists some other useful JS shell links at:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Shells



About the other questions, no...you do not get compiled binaries out of any of these. The fastest JS execution models use what's called a "just in time" (JIT) compiler, and that basically compiles lines of source code into machine code as it interprets the source code, and skips the recompilation step on a later run of the same code if the data types of variables haven't changed. There's no easy way to compile code without knowing exact data types of variables, argument types and return types of functions, etc.



At the Windows command line, running a .js program (or double-clicking in the explorer) will run WSH and get the older version. This is what you want for Window scripting. You could modify the filetype settings to run .js under Node.JS or something, but that would likely mess up other scripts.



OSX/Linux/Unix sh/bash shells can use scripts with a "shebang" line to invoke the Node.JS interpreter to run the rest of the script file as a JS program. These will run just like compiled binary commands, for any command line use. For a GUI, consider running in a standalone HTML file with embedded JS. You have all of DOM to create your GUI and a modern JS for your code.

Answer 2

JavaScript it primarily used as a scripting language for web applications that runs in the browser. You can also run JavaScript on a server using Node.JS which is normally used as a backend for web applications. There are other applications that have adopted JavaScript as a scripting language, for example Chrome extensions are written in JavaScript, but you can't arbitrarily choose to use JavaScript as a scripting langue for something, the program you are scripting has to have been written to use JavaScript. I am not aware of any tools that allows to script command lines in JavaScript, but you could probably achieve something similar in Node.JS. JavaScript is normally interpreted, there is no general use JavaScript compiler.

Answer 3

Not necessarily, it can be used soly to create smaller applications, but once it reaches a certain size it can cause memory issues