Duktape Copying Objects

Question

I've got a duktape stack with the item on the top of the stack being effectively a JSON object, built with duk_push_string() / duk_put_prop_string().

My resulting object in javascript land is called 'obj', and I want to create a copy of obj, and store it within the same structure (a cached copy of the original data if you will).

i.e.

obj.id
obj.info
    obj.orig.id
    obj.orig.info

I though I may be able to do it by duplicating the entry at the top of the stack, then pushing it onto the stack like this:

duk_dup_top(ctx) ;
duk_put_prop_string(ctx, -2, "orig");

But when I run the program, I get a fatal error message: uncaught: 'cyclic input'

Any hints?

Ta, T

I can add json_data in with put_prop if I use duk_decode, but I can't find a way of getting JSON data out (i.e. converting the top to JSON in the first place).