设置select中value="paraValue"的Item为选中
//document.all.objSelect.value = objItemValue;

//得到select的当前选中项的value
//var currSelectValue = document.all.objSelect.value;

//得到select的当前选中项的text
//var currSelectText = document.all.objSelect.options[document.all.objSelect.selectedIndex].text;

//得到select的当前选中项的Index
//var currSelectIndex = document.all.objSelect.selectedIndex;

//清空select的项
// document.all.objSelect.options.length = 0;

http://www.corange.cn/archives/2008/10/2118.html