Is there a way to test circular reference in JavaScript?

I’m making a game, and I’ve come across a problem… When I try to save, JSON fails and reports that circular reference is being made somewhere. I don’t think it actually is, I can’t see it, so is there an algorithm or anything which could tell me where it is exactly (between which objects and stuff)? Also, is there a JSON alternative that can save circular reference? I’m running a node.js server, I saw this, but I can’t get it to work (it’s not made as a module i can require() in my code).