判断CheckBoxList必须选中一个

function isselect()

{

var dutyflag=0;

var checkobj = document.getElementById( "CheckBoxList2 ");

var checks = checkobj.getElementsByTagName( "input ");

for(var n=0;n <checks.length;n++)

{

if(checks
.type== "checkbox " && checks
.checked==true)

{

dutyflag=1;

}

}

if(dutyflag==0)

{

alert( "至少要选择1个部门 ");

return false;

}

return true;

}