js this function call does not need to capture id, name or tag name again

<input type="button" value="Save" class="btn1" onClick="nullCheck(this)"/>
<script>
function nullCheck(obj)
{
...//Write the code for the functions you need here
}
</script>

<input type="checkbox" name='agentType' value="exclusive" onchange="clickAgenter(this)">

function clickAgenter(obj){
if($(obj).attr("checked")=="checked"){
$("[name='agentType']").removeAttr("checked");//Cancel all
$(obj).attr("checked","checked")
}
}