範例 - JavaScript 存取 Radio Button

簡單來說就是逐一比對相同name屬性的input控制項

HTML part：

<form id="demoForm" method="post" action="...">
     <input type="radio" name="statisticType" value="region" checked="checked" />依地區
     <input type="radio" name="statisticType" value="time" />依時間<br />
</form>

JavaScript part：

var sType;
var demo = document.getElementById("demoForm");

for (var i = 0; i < demo.statisticType.length; i++) {
    if (demo.statisticType[i].checked) {
        sType = demo.statisticType[i].value;
        break;
    }
}

alert(sType);