Spidermonkey – Execute Javascript From Console

SpiderMonkey is the code-name for the Mozilla’s C implementation of JavaScript. This is useful to test part of our JavaScript from the console or in scripts.

In Debian we have a package called spidermonkey-bin.

1apt-get install spidermonkey-bin

After installing you will have a program called smjs.

If you start the program without parameters you will get a Javascript shell, in which you can write and test javascript.

 1$ /usr/bin/smjs
 2js> function test() {
 3print('test');
 4}
 5js> test
 6function test() {
 7    print("test");
 8}
 9js> test();
10test
11js> function test() {
12print('test');
13test2(123);
14}
15js> function test2(param) {
16print ('test2: ' + param);
17}
18js> test();
19test
20test2: 123
21js>

To exit the shell, just press “Ctrl+D“.

It’s important to note that in spidermonkey you doesn’t have the “document” Object. If you want to print out text, you cant use document.write, you should use print.

1document.write('test'); // In browser
2print('test'); //spidermonkey

You can also make smjs to execute the content of a file.

1$ /usr/bin/smjs test-local.js
2Rand: 407
3Old: 600
4New: 800
5Result: old