我的写法，请多指教
<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<meta name="Generator" content="EditPlus®">
<meta name="Author" content="">
<meta name="Keywords" content="">
<meta name="Description" content="">
<title>Document</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="checked";
}
// 任务1
}
function clearall(){
var hobby = document.getElementsByName("hobby");
for(var i=0;i<hobby.length;i++){
hobby[i].checked="";
}
// 任务2
}
function checkone(){
var j=document.getElementById("wb").value;
var i=parseInt(j);
if(i>=1 && i<=6){
var hobby=document.getElementsByName("hobby");
hobby[i-1].checked="checked";
}else{
alert("请输入1-6的整数！");
}
// 任务3
}
</script>
</body>
</html>
