Yes. You could do either of the following (but not both).
// form1.page1.dropDown::exit - (JavaScript, client)
form1.page1.textField.rawValue = this.rawValue;
The second option has the advantage of making the field 'textField' read-only (which may or may not be desirable).
// form1.page1.textField::calculate - (JavaScript, client)
this.rawValue = form1.page1.dropDown.rawValue;
Steve