<form name=f>
<input type=radio name=txt>
<input type=radio name=txt>
<input type=radio name=txt>
<input type=radio name=txt>
<input type=button onclick="test()" vaLUE="TEST">
</form>
<script>
function test()
{
var a=document.f;
if(a.txt) alert("存在")
else
alert("不存在")}
</script>
<input type=radio name=txt>
<input type=radio name=txt>
<input type=radio name=txt>
<input type=radio name=txt>
<input type=button onclick="test()" vaLUE="TEST">
</form>
<script>
function test()
{
var a=document.f;
if(a.txt) alert("存在")
else
alert("不存在")}
</script>
<input type=radio name=txt>
<input type=radio name=txt>
<input type=radio name=txt>
<input type=radio name=txt>
<input type=button onclick="test()" vaLUE="TEST">
</form>
<script>
function test()
{
var a=document.f;
if(a.txt)
alert("txt存在")
else
alert("txt不存在")if(a.txt2)
alert("txt2存在")
else
alert("txt2不存在")
}
</script>
<input type=radio name=txt>
<input type=radio name=txt>
<input type=checkbox name=txt>
<input type=checkbox name=txt>
<input type=button onclick="test()" vaLUE="TEST">
</form>
<script>
function test()
{
var a=document.f;
if(a.txt)
{
for(i=0;i<a.txt.length;i++)
{
alert("有一个名为txt的"+a.txt[i].type);
}
}
else
alert("txt不存在")if(a.txt2)
alert("txt2存在")
else
alert("txt2不存在")
}
</script>
<input type=radio name=txt>txt
<input type=radio name=txt>txt
<input type=radio name=txt3>txt3
<input type=radio name=txt4>txt4
<input type=button onclick="test('txt')" vaLUE="test txt">
<input type=button onclick="test('txt2')" vaLUE="text txt2">
<input type=button onclick="test('txt3')" vaLUE="test txt3">
<input type=button onclick="test('txt5')" vaLUE="text txt5">
</form>
<script>
function test(strName){alert(strName+(document.f(strName)?"":"不")+"存在");}
</script>