select下拉框的onkeydown事件，修改下拉框的值
function catch_keydown(sel){
switch(event.keyCode) {
case 13: //回车键
event.returnValue = false;
break;
case 27: //Esc键
sel.options[sel.selectedIndex].text = oldText;
sel.options[sel.selectedIndex].value = oldValue;
event.returnValue = false;
break;
case 8: //空格健
var s = sel.options[sel.selectedIndex].text;
s = s.substr(0,s.length-1);
if (sel.options[0].value==sel.options[sel.selectedIndex].text){
sel.options[sel.selectedIndex].value=s;
sel.options[sel.selectedIndex].text=s;
}
event.returnValue = false;
break;
}
if (!event.returnValue && sel.onchange)
sel.onchange(sel)
}select下拉框的onkeypress事件，修改下拉框的值
function catch_press(sel){
if(sel.selectedIndex>=0){
var s = sel.options[sel.selectedIndex].text + String.fromCharCode(event.keyCode);
if (sel.options[sel.selectedIndex].value==sel.options[sel.selectedIndex].text){
sel.options[sel.selectedIndex].value=s;
sel.options[sel.selectedIndex].text=s;
}
event.returnValue = false;
if (!event.returnValue && sel.onchange)
sel.onchange(sel)
}
}select下拉框的onfocus事件，保存下拉框原来的值
function catch_focus(sel) {
oldText = sel.options[sel.selectedIndex].value;
oldValue = sel.options[sel.selectedIndex].value;
} 使用方法
<!--调用--> <select style='width:130px;z-index:-1' name='tmpSel' onkeydown=catch_keydown(this) onkeypress=catch_press(this) onfocus=catch_focus(this)> <option value=''></option> <option value=''>A</option> <option value=''>B</option> <option value=''>C</option> </select>
