javascript-for-in with checker value

javascript for in 


s="";dl="";
s2="value1,value2,value3,value4"
s3=s2.split(",");
for (x in s3){
s1=s3[x];if ($('#'+s1).is(":checked")){s=s+dl+s1;dl=",";}
}

reset checker by javascript (ok)

for (x in COMPANYas){
s1=COMPANYas[x];
document.getElementById(s1).checked = false; //ok
//$('#'+s1).attr("checked", false); // not ok
}

<script type=text/javascript>
function validate(){
if (document.getElementById('remember').checked){
          alert("checked") ;
}else{
alert("You didn't check it! Let me check it for you.")
}
}
</script>

<input id="remember" name="remember" type="checkbox" onclick="validate()" />