怎样在第二次输入序号后，取消第一次的选项，只选第二次的序号
直接调用clearall()这个函数
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
</head>
<body>
<form>
请选择你爱好:<br>
<input type="checkbox" name="hobby" id="hobby1"> 音乐
<input type="checkbox" name="hobby" id="hobby2"> 登山
<input type="checkbox" name="hobby" id="hobby3"> 游泳
<input type="checkbox" name="hobby" id="hobby4"> 阅读
<input type="checkbox" name="hobby" id="hobby5"> 打球
<input type="checkbox" name="hobby" id="hobby6"> 跑步 <br>
<input type="button" value = "全选" onclick = "checkall();">
<input type="button" value = "全不选" onclick = "clearall();">
<p>请输入您要选择爱好的序号，序号为1-6:</p>
<input id="wb" name="wb" type="text" >
<input name="ok" type="button" value="确定" onclick = "checkone();">
</form>
<script type="text/javascript">
function checkall(){
var hobby = document.getElementsByTagName("input");
for(var i=0;i<hobby.length;i++){
hobby[i].checked = true;
}
}
function clearall(){
var hobby = document.getElementsByName("hobby");
for(var i=0;i<hobby.length;i++){
hobby[i].checked = false;
}
}
function checkone(){
var hobby = document.getElementsByName("hobby");
var j=document.getElementById("wb");
if(parseInt(j.value)>hobby.length||parseInt(j.value)<1){
alert("请输入正确的数值");
j.value = "";
}else{
for(var i=0;i<hobby.length;i++){
hobby[i].checked = false;
}
hobby[parseInt(j.value)-1].checked=true;
j.value = "";
}
}
</script>
</body>
</html>