<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title></title>
<script type="text/javascript" src="jquery-3.2.1.min.js"></script>
</head>
<body>
<form name="a">
<select name="selecta" size="1" id="selectb" >
<option value="a">1</option>
<option value="b">2</option>
<option value="c">3</option>
</select>
<button onclick="foo()">选择</button>
</form>
<script type="text/javascript">
function foo(){
var i = document.getElementById("selectb").selectedIndex;
var v1 = document.getElementsByTagName("option")[i].value;// a
var v2 = document.getElementsByTagName("option")[i].text;// 1
var v3 = $("#selectb option:selected").val();// b
var v4 = $("#selectb option:selected").text();// 2
var v5 = $("#selectb").val();// c
var v6 = $("#selectb").text();// 1 2 3
var v7 = $("#selectb").text();// 1 2 3
var v8 = $("#selectb").find("option:selected").val(); // a
var v9 = $("#selectb").find("option:selected").text(); // 1
alert(v1);
}
</script>
</body>
</html>