I wrote this in order to implement my regular expression visualizer.
There’s a live example below. Clicking on a button requests some JSON text from the server and parses it on the client. The source code to the example is here.
(When it runs off my web site, the debugger in the example displays a warning about not being able to connect to the LPS server. This means that the debugger can’t evaluate expressions, as it could if you were running it off the SDK. I’m just using the debugger here to print inspectable representations of the JSON parse results, and the warning doesn’t affect this.)
It’s open source, of course. (MIT License.)