利用复选框和隐藏控件设计多选题

一直输出不了，有人指点一下吗

<form name=frmLx4> 
大狗的儿子是谁<br> 
<input type=checkbox name=TZ value=1>麻雀<br> 
<input type=checkbox name=TZ value=2>小狗<br> 
<input type=checkbox name=TZ value=3>二狗<br> 
<input type=checkbox name=TZ value=4>猴子<br> 
<input type=hidden name=hidDA value=2> 
<input type=hidden name=hidDB value=3> 
<input type=button value="OK" onClick="funGo4()"> 
</form> 
<script> 
function funGo4(){ 
var dx=document.getElementsByClassName("TZ")
for(var i=0;i<=dx.TZ.length;i++){ 
if(dx.TZ[i].checked){ 
da=dx.TZ[i].value 
break 
} 
} 
if(da==dx.hidDA.value){ 
alert("OK") 
}else{ 
alert("wrong") 
} 
} 
</script> 

<form name=frmLx4>
            大狗的儿子是谁<br>
            <input type=checkbox name='TZ' value='1'>麻雀<br>
            <input type=checkbox name='TZ' value='2'>小狗<br>
            <input type=checkbox name='TZ' value='3'>二狗<br>
            <input type=checkbox name='TZ' value='4'>猴子<br>
            <input type=hidden name='hidDA' value='2'>
            <input type=hidden name='hidDB' value='3'>
            <input type=button value="OK" onClick="funGo4()">
        </form>
        <script>
            function funGo4() {
                var dx = document.getElementsByName("TZ")
                var da = ''
                for(var i = 0; i < dx.length; i++) {
                    if(dx[i].checked) {
                        da = dx[i].value
                        break
                    }
                }
                var hidDA = document.getElementsByName("hidDA")
                if(da == hidDA[0].value) {
                    alert("OK")
                } else {
                    alert("wrong")
                }
            }
        </script>

getElementsByClassName 获取的是 class
getElementsByName 才是获取 name 属性