哪里错了？怎么点全选选项就都没了？
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 = "a();">
<input type="button" value = "全不选" onclick = "c();">
<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 = "e();">
</form>
<script type="text/javascript">
function a()
{
var b=document.getElementsByTagName("input");
for(var i=0;i<b.length;i++)
{
if(b[i].type="checkbox")
{
b[i].checked=true;
}
}
}
function c()
{
var d=document.getElementsByName("hobby");
for(var j=0; j<d.length;j++)
{
d[j].checked=false;
}
}
function e()
{
var f=document.getElementById("wb").value;
var g=document.getElementById("hobby"+f);
g.checked=true;
}
</script>
