function checkone(){
var j=document.getElementById("wb").value;
var hobby = document.getElementById("hobby"+j);
hobby.checked = true; }
每项的id就是"hobby+(1~6)"，拆分就是"hobby"+"1~6"组成id。那么这里用j来获取数字，再拼接给hobby，组成完整的id
不清楚了，我也刚做这题，题目写的不清不楚的
但是这样做只是单选，不是复选
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<titlntsByName,getElementsBe>无标题文档</title>
</head>
<body>
<form>
请选择你爱好:<br>
<input type="checkbox" name="hobby" id="hobby1"> 1音乐
<input type="checkbox" name="hobby" id="hobby2"> 2登山
<input type="checkbox" name="hobby" id="hobby3"> 3游泳
<input type="checkbox" name="hobby" id="hobby4"> 4阅读
<input type="checkbox" name="hobby" id="hobby5"> 5打球
<input type="checkbox" name="hobby" id="hobby6"> 6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");
// 任务1
for(var i=0;i<hobby.length;i++)
{
if(hobby[i].type == "checkbox")
{
hobby[i].checked = true;
}
}
}
function clearall(){
var hobby = document.getElementsByName("hobby");
// 任务2
for(var i=0;i<hobby.length;i++)
{
hobby[i].checked = false;
}
}
function checkone(){
var j=document.getElementById("wb").value;
// 任务3
var hobby = document.getElementById("hobby"+j);
hobby.checked = true;
}
</script>
</body>
</html>
j :获取输入框的值
hobby : 获取与j相应的id
选中相应的复选框
代码应该要完整一点