<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<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 t=0;t<hobby.length;t++)
{ if(hobby[t].type = "checked")
{
hobby[t].checked=true;
}
}
// 任务1
function clearall(){
var hobby = document.getElementsByName("hobby");
for(var t = 0;t<hobby.length;t++)
{
hobby[t].checked = false;
}
// 任务2
}
function checkone(){
var j=parseInt(document.getElementById("wb").value);
if(j>0 && j<=6){
document.getElementById('hobby'+j).checked=true;
}
else
alert("请输入正确的选项");
// 任务3
}
</script>
</body>
</html>
checkall里面if语句要用 == 不是=
把checkall()函数里面的这个if判断去掉就可以了