Question: I have a C++ desktop application (written in wxWidgets) and I want to add support for some scripting language.

Scripting would mostly be used for run-time conversions of strings, numbers and dates by user supplied JavaScript code.

I'd like to use JavaScript because it is widely used and everyone is familiar with the syntax. 

Googling around, it seems I have two options:

* SpiderMonkey from Mozilla
* JavaScriptCore from WebKit

Has anyone tried those? Which one would be easier to set up? 
Do you know of some other implementation that is better for my needs?

BTW, I target Windows and Linux platforms.

Answer: 
Of course, you could also use [Lua](http://lua.org), which not only is designed specifically for this, it's vastly faster than any JS.

Also, it's has well-designed semantics, a very minimal core, simple C API, great portability, a very mature [JIT](http://luajit.org), the most helpful online community I've seen, etc...
JavaScriptCore has a stable C API (and ABI), and has been available (and used as) a standard system framework on macos.

[edit: oh, and it works on linux and windows as a standalone library, although i believe only debian distributes it as such]