页面问题

Question

for(i=0;i<document.getElementsBytagName("INPUT").length;i++)
{
if(document.getElementsBytagName("INPUT").type=="checkbox" && document.getElementsBytagName("INPUT").checked)
{
alert(document.getElementsBytagName("INPUT").value)}
}

Answer 1

for(i=0;i<document.getElementsBytagName("INPUT").length;i++)
{
if(document.getElementsBytagName("INPUT")[i].type=="checkbox" && document.getElementsBytagName("INPUT")[i].checked)
{
alert(document.getElementsBytagName("INPUT")[i].value)}
}
sorry

Answer 2

for(i=0;i<document.getElementsByTagName("INPUT").length;i++)
{
if(document.getElementsByTagName("INPUT")[i].type=="checkbox" && document.getElementsByTagName("INPUT")[i].checked)
{
alert(document.getElementsByTagName("INPUT")[i].value)}
}
sorry

Answer 3

<input type=checkbox id=id1>
<input type=checkbox id=id2>
<input type=checkbox id=id3>
<input type=checkbox id=id4>
<input type=button value=check() onclick=check()>
<script>
function check(){
var o=document.getElementsByTagName("input");
for(i=0;i<o.length;i++)if(o[i].checked)alert(o[i].id)
}
</script>