gistfile1.js

function clone(obj, callback) {
    var from = window.location.origin;
    var wrapper = {'__clone__': true};
    wrapper.__data__ = obj;
   var listener = function(e) {
        if(e.origin === from && e.data.__clone__) {
            callback(e.data.__data__);
            window.removeEventListener('message', listener);
        }
   };
    window.addEventListener('message', listener);
    window.postMessage(wrapper, from);
}