本文介绍如何使用JavaScript实现无需点击提交按钮的下拉菜单跳转功能。通过监听select元素的onchange事件，获取选中选项的value值，并直接赋值给window.location，实现页面即时跳转。代码包含HTML结构及JS逻辑，支持禁用脚本时的降级处理。
JavaScript实现无按钮直接跳转的下拉菜单
传统
本例旨在省略“Go There”按钮，实现选择菜单项后自动跳转。
Html代码
代码如下:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>转移菜单</title>
<script type="text/javascript" src="转移菜单.js"></script>
</head>
<body>
<form>
<select id="newLocation">
<option selected="selected" value="">Select a topic</option>
<option value="topic1.html">topic1</option>
<option value="topic2.html">topic2</option>
<option value="topic3.html">topic3</option>
<option value="topic4.html">topic4</option>
<option value="topic5.html">topic5</option>
</select>
<!--当浏览器不支持javascript或者禁用脚本运行时被调用-->
<noscript>
<input type="submit" value="Go There!"/>
</noscript>
</form>
</body>
</html>Javascript脚本
代码如下:
window.onload=initForm;
//防止页面缓存，无法触发onload
window.onunload=function(){}
function initForm(){
document.getElementById("newLocation").selectIndex=0;
document.getElementById("newLocation").onchange=jumpPage;
}
function jumpPage(){
var newLoc=document.getElementById("newLocation");
var newPage=newLoc.options[newLoc.selectedIndex].value;
if (newPage!=""){
window.location=newPage;
}
}