After the first release of NativeScript I decided to spend some time playing with JavaScriptCore engine. We use it in NativeScript bridge for iOS and so far I heard good words about it from my colleagues. So I decided to play with JavaScriptCore and compare it to V8 engine.
At present NativeScript supports Android and iOS platforms only. We have plans to add support for Windows Phone as well and I thought it would be nice to have some experience with JavaScriptCore on Windows Phone before we make a choice between Chakra and JavaScriptCore.
The first difference I noticed between JavaScriptCore and V8 is that it has an API much closer to C style while the V8 API is entirely written in C++. This is not an issue and sometimes I consider it as an advantage.
The second difference, in my opinion, is that JavaScriptCore API is more simpler and expose almost no extension points. From this point of view I consider the V8 API the better one. Compared to JavaScriptCore, V8 provides much richer API for controlling internals of the engine like JIT compilation, object heap management and garbage collection.
Nevertheless it was fun to play with JavaScriptCore engine. You can find a sample project at GitHub.
Could you please share the steps to build JavaScriptCore for Windows Phone 8 and also you mention about Chakra here, is it possible to use Chakra APIs in windows phone 8 or in other words, is it possible to embed Chakra engine in Windows Phone 8 app?
You can look at the following wiki page https://github.com/appcelerator/hyperloop/wiki/Building-JavaScriptCore-for-Android#to-build-on-windows for instructions to build JavaScriptCore for Windows Phone. You may read my blog post about Chakra here http://ezw.oum.mybluehost.me/blog/2014/09/10/embedding-chakra-javascript-engine-on-windows-phone/