Pass object through dataTransfer

You should pass the object to JSON.stringify before using setData because you can only store strings.

var j = JSON.stringify(foo);
e.originalEvent.dataTransfer.setData("foo", j);

And the other way round you have to reconvert the string to an object:

var obj = JSON.parse(e.originalEvent.dataTransfer.getData("foo"));
console.log("foo is:", obj);

See this working Fiddle