<script src="https://cdn.staticfile.org/jquery/2.2.4/jquery.min.js"></script>

<input type="radio" name="radio" value="1" onclick="radio()" />

<label>a</label>

​

<input type="radio" name="radio" value="2" onclick="radio()" /><label>b</label>

​

<input type="radio" name="radio" value="3" onclick="radio()" /><label>c</label>

​

<input type="radio" name="radio" value="4" onclick="radio()" /><label>d</label>

function radio() {

    var a = $(":radio[name='radio']:checked + label").text();

    alert("选中的radio的值是：" + a);

}