<html>
<head>
<script type="text/javascript">
function change(menuObj){
var i=menuObj.selectedIndex;
//如何得到change 前的menuObj.selectedIndex？
}
</script>
</head>
<body>
<form>
<select onchange="change(this)">
<option selected>select option</option>
<option value="1" id="option1">option1</option>
<option value="2" id="option2">option2</option>
<option value="3" id="option3">option3</option>
</select>
</form>
</body>
</html>
<head>
<script type="text/javascript">
function change(menuObj){
var i=menuObj.selectedIndex;
//如何得到change 前的menuObj.selectedIndex？
}
</script>
</head>
<body>
<form>
<select onchange="change(this)">
<option selected>select option</option>
<option value="1" id="option1">option1</option>
<option value="2" id="option2">option2</option>
<option value="3" id="option3">option3</option>
</select>
</form>
</body>
</html>
<script type="text/javascript">
window.attachEvent("onload", function() {
var slcs = document.getElementsByTagName("SELECT");
for (var i=0; i<slcs.length; i++) {
var a = document.createAttribute("last")
a.value = slcs[i].selectedIndex;
slcs[i].setAttributeNode(a);
a = document.createAttribute("current")
a.value = slcs[i].selectedIndex;
slcs[i].setAttributeNode(a);
}
});
function chgAction(slc) {
slc.setAttribute("last", slc.getAttribute("current"));
slc.setAttribute("current", slc.selectedIndex);
}
function change(menuObj) {
chgAction(menuObj);
var i = menuObj.selectedIndex;
var l = menuObj.getAttribute("last"); alert("当前 selectedIndex: " + i + "\n" +
"上次 selectedIndex: " + l);
}
</script>
<select onchange="JavaScript: change(this);">
<option value="1">a</option>
<option value="2">b</option>
<option value="3" selected="selected">c</option>
</select>
function change(menuObj){
var i=menuObj.selectedIndex;
if(oldIndex != null)
{
alert(oldIndex);
}
oldIndex = i;
}
</script>