在线运行代码 - 菜鸟教程

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>菜鸟教程(cainiaoplay.com)</title>
<script>
function displayResult(){
	var radios = document.getElementsByName('colors');
	for (var i = 0, length = radios.length; i < length; i++) {
		if (radios[i].checked) {
			// 弹出选中值
			alert(radios[i].value);
			// 选中后退出循环
			break;
		}
	}
}
</script>
</head>
<body>

<form>
你更喜欢哪种颜色?<br>
<input type="radio" name="colors" id="red" value="red">红色<br>
<input type="radio" name="colors" id="blue" value="blue">蓝色<br>
<input type="radio" name="colors" id="green" value="green">绿色
</form>
<button type="button" onclick="displayResult()">显示选中的值</button>

</body>
</html>
源代码

动行结果
