receives a JS object which may have cycles and returns another one with repeated cycles replaced by '[removed]' string. Use return instead if you don't mind them not being signalled.

removeCycles.js

var removeCycles = function(o) {
    var seen = [];

    var s = JSON.stringify(o, function(k, v) {
       if (v !== null && typeof v === 'object') {
            if (seen.indexOf(v) !== -1) {
                //return;
                v = '[removed]';
            }
            else {
                seen.push(v);
            }
        }
        return v;
    });

    return JSON.parse(s);
};