6.2 动态改变菜单

省市区类型；
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <script>
        window.onload = initForm;
        function initForm() {
            jumpPage();
            document.getElementById("province").onchange = jumpPage;
        }
        function jumpPage() {
            var p = document.getElementById ("province");
            var c = document.getElementById ("city");

            var info = [["杭州", "宁波"],["南京","苏州"]];
            var select2 = info[p.selectedIndex];

            for (var a = 0; a < select2.length; a++) {
                c.options[a] = new Option(select2[a]);
            }
        }
    </script>
</head>
<body>
<form action="" id="myForm">
    <select id="province">
        <option value="0" selected>浙江</option>
        <option value="1">江苏</option>
    </select>
    <select id="city">
    </select>
</form>
</body>
</html>