通过checkbox选择以逗号拼接删除字符串

<script type="text/javascript">
$(function(){
var ids = "1,3";
$("#ids").val(ids);
var ckArray = ids.split(",");
$("input[type='checkbox']").each(function(){
for(var i = 0;i < ckArray.length ; i++){
if(ckArray[i] == $(this).val()){
$(this).attr("checked","checked");
}
}
})
});
function add(ck){
var ckval = $("#ids").val();
if(ck.checked){
if(ckval == ""){
ckval = $(ck).val();
}else{
ckval = ckval +","+ $(ck).val();
}
$("#ids").val(ckval);
}else{
var ckArray = ckval.split(",");
for(var i = 0;i < ckArray.length ; i++){
if(ckArray[i] == $(ck).val()){
ckArray[i] = null;
}
}
ckval = ckArray.join(",");
ckval = ckval.replace(/,,/,',').replace(/^,/, '').replace(/,$/, '');
$("#ids").val(ckval);
}
}
</script>

<input type="text" name="ids" id="ids"/>
<input type="checkbox" value="1" onclick="add(this)"/>
<input type="checkbox" value="2"  onclick="add(this)"/>
<input type="checkbox" value="3"  onclick="add(this)"/>
<input type="checkbox" value="4"  onclick="add(this)"/>