让Select列表各项上移和下移的Js代码-优快云博客

本文介绍了一个使用JavaScript实现的网页功能，该功能允许用户通过按钮操作来调整Select下拉列表中选项的位置。当用户点击向上或向下按钮时，选中的列表项会相应地向上或向下移动一个位置。

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<html>
<head>
<title>Select列表各项上移和下移</title>
<script>
function move(index,to) {
var list = document.form.list;
var total = list.options.length-1;
if (index == -1) return false;
if (to == +1 && index == total) return false;
if (to == -1 && index == 0) return false;
var items = new Array;
var values = new Array;
for (i = total; i >= 0; i--) {
items[i] = list.options[i].text;
values[i] = list.options[i].value;
}
for (i = total; i >= 0; i--) {
if (index == i) {
list.options[i + to] = new Option(items[i],values[i + to], 0, 1);
list.options[i] = new Option(items[i + to], values[i]);
i--;
}
else {
list.options[i] = new Option(items[i], values[i]);
}
}
list.focus();
}
function submitForm() {
var list = document.form.list;
var theList = "?";
for (i = 0; i <= list.options.length-1; i++) {
theList += "list" + list.options[i].value + "=" + list.options[i].text;
if (i != list.options.length-1) theList += "&";
}
location.href = document.form.action + theList;
}
</script>
</head>
<body>
<form method="GET" action="" name="form">
<table>
<tr>
<td align="middle">
<select name="list" size="4">
<option value="1">ASP</option>
<option value="2">PHP</option>
<option value="3">JSP</option>
<option value="4">JAVA</option>
</select><br><br>
<input type="button" value="submit" onClick="submitForm()">
</td>
<td valign="top">
<input type="button" value="↑"
onClick="move(this.form.list.selectedIndex,-1)"><br><br>
<input type="button" value="↓"
onClick="move(this.form.list.selectedIndex,+1)">
</td>
</tr>
</table>
</form>
</body>
</html>