Javascript – Executing JavaScript without a browser

command-linejavascriptscriptingunixv8

I am looking into Javascript programming without a browser. I want to run scripts from the Linux or Mac OS X command line, much like we run any other scripting language (ruby, php, perl, python…)

$ javascript my_javascript_code.js

I looked into spider monkey (Mozilla) and v8 (Google), but both of these appear to be embedded.

Is anyone using Javascript as a scripting language to be executed from the command line?

If anyone is curious why I am looking into this, I've been poking around node.js. The performance of node.js makes me wonder if javascript may be a viable scripting language for processing large data.

Best Solution

Main Answer

Yes, to answer your question, it is possible to use JavaScript as a "regular" scripting language from the command line, without a browser. Since others have not mentioned it yet, I see that it is worth mentioning:

On Debian-based systems (and this includes Ubuntu, Linux Mint, and aptosid/sidux, at least), besides the options of installing Rhino and others already mentioned, you have have other options:

  • Install the libmozjs-24-bin package, which will provide you with Mozilla's Spidermonkey engine on the command line as a simple js24, which can be used also as an interactive interpreter. (The 24 in the name means that it corresponds to version 24 of Firefox).

  • Install the libv8-dev package, which will provide you Google's V8 engine. It has, as one of its examples, the file /usr/share/doc/libv8-dev/examples/shell.cc.gz which you can uncompress and compile very simply (e.g., g++ -Os shell.cc -o shell -lv8).

  • Install the package nodejs and it will be available both as the executable nodejs and as an alternative (in the Debian-sense) to provide the js executable. JIT compilation is provided as a courtesy of V8.

  • Install the package libjavascriptcoregtk-3.0-bin and use WebKit's JavaScriptCore interpreter (jsc) as a regular interpreter from the command-line. And this is without needing to have access to a Mac. On many platforms (e.g., x86 and x86_64), this interpreter will come with a JIT compiler.

So, with almost no compilation you will have three of the heavy-weight JavaScript engines at your disposal.

Addendum

Once you have things installed, you can simply create files with the #!/usr/bin/js shebang line and things will just work:

$ cat foo.js 
#!/usr/bin/js

console.log("Hello, world!");
$ ls -lAF /usr/bin/js /etc/alternatives/js /usr/bin/nodejs
lrwxrwxrwx 1 root root      15 Jul 16 04:26 /etc/alternatives/js -> /usr/bin/nodejs*
lrwxrwxrwx 1 root root      20 Jul 16 04:26 /usr/bin/js -> /etc/alternatives/js*
-rwxr-xr-x 1 root root 1422004 Apr 28 20:31 /usr/bin/nodejs*
$ chmod a+x foo.js 
$ ./foo.js 
Hello, world!
$ js ./foo.js
Hello, world!
$