js判断radio是否选中并取值

<script type="text/javascript">function check(){var len=document.form1.r1.length;for(i=0;i<len;i++){if(document.form1.r1[i].checked){alert(document.form1.r1[i].value);return;}}}</script><form name="form1"><input type="radio" name="r1" value="1" />1     <input type="radio" name="r1" value="2" />2     <input type="radio" name="r1" value="3" />3<input type="button" value="button" onclick="check()" /></form>