js中的checkbox按钮用法

Question

function onchckClick(ctrl){
   
       var chkstatus=document.getElementById("chk_upstatus");
       if(chkstatus.checked){
            var j=0;
            var chks=document.getElementsByName("chks");
            for(var i=0;i<chks.length;i++){
                var one_chk=chks[i];
                if(one_chk.checked){
                    j++;
                    if(j>1){
                       // alert("对不起不能选俩");
                       ctrl.checked=false;
                       return ;
                    }                }
            }
            
            if(ctrl.checked){//dh
                id=ctrl.value;
                var name=document.getElementById("name_"+id).value;
                var price=document.getElementById("price_"+id).value;
                document.getElementById("<%= this.txt_name.ClientID %>").value=name;
                document.getElementById("<%= this.txt_price.ClientID %>").value=price;
            }else{
                document.getElementById("<%= this.txt_name.ClientID %>").value="";
                document.getElementById("<%= this.txt_price.ClientID %>").value="";
            }
        }
      
    }
想实现的功能是当我点击chkstatus.checked,里面只有一个checkbox按钮能显示  多余的话false,( 不会做的)当我取消chkstatus.checked按钮时,里面的checkbox全部不选中

Answer 1

var   num=0; 
var   a=document.getElementsByTagName( "input ") 
for(var   i=0;i <a.length;i++){ 
if(a[i].type== "checkbox "){ 
if(a[i].checked==true){ 
num=num+1; 
} 
} 
} 
alert(num) 
if(num==0){ 
alert('') 
}checkbox的name="chks"
document.getElementsByName( "chks").lengthif(chkstatus.checked){
}
else
{
//取消选择var chs = document.getElementsByName ("chks");
            for(var i = 0; i<chs.length ; i++)
            {
                chs[i].checked = false ;}