jQuery – Illegal invocation

I think you need to have strings as the data values. It’s likely something internally within jQuery that isn’t encoding/serializing correctly the To & From Objects.

Try:

var data = {
    from : from.val(),
    to : to.val(),
    speed : speed
};

Notice also on the lines:

$(from).css(...
$(to).css(

You don’t need the jQuery wrapper as To & From are already jQuery objects.