function def()

{

    var key = document.getElementById ('selectarea'); //select list

    var value = document.getElementById ('DocAuthor'); //input text

 

　　//两种不同的取值

    value.value = key.options[key.selectedIndex].text; //取得select list已选项的文本(显示给用户的值)赋给input text

    value.value = key.options[key.selectedIndex].value; //取得select list已选项的value(正真传递的值)赋给input text

}