Is there any API debug tool with fully functional javascript support in preview mode?

I am actually searching the way to comfortably debug API urls which in my case needs that the API testing tool being able to show response data as a web page (aka preview mode) with java-script support. There are a lot of tools which can show response as web page but without javascript.

I am using symfony2 framework and it provides cool dumping function (which needs JS for nice output) and also cool web-debug toolbar (which is not works at all without JS because uses XHR requests). So the lack of JS support results in looong non-understandable dump() reports, and non-working web-debug toolbar. So the debug process looks like reading a stone-edge var_dump()'s huge outputs.