在任务三中，我怎么判断用户输入的是数字而不是字母abc;例如用户输入的是12ab3,我应该如何跳过ab,将123复选框勾上？
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</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 j=document.getElementById("wb").value;
var hobby = document.getElementsByTagName("input");
for (var i = 0; i < j.length; i++)
{
if(j[i]>6||j[i]<1){
alert("你丫的参数输错了");
continue;
}
hobby[j[i]-1].checked=true;
// alert(typeof parseInt(j[i]));
};
// 任务3
}
</script>
</body>
</html>
