전체선택 전체취소

<script language='javascript'>
<!--
    var nData;
    function selectAll( obj )
    {
        var chkBox = obj.form.elements['aTable[]'];
        var chkLen = chkBox.length;

        if( !nData )
        {
            for( i=0; i<chkLen; i++ )
            {
                chkBox[i].checked = 1;
            }
            nData = 1;
        }
        else
        {
            for( i=0; i<chkLen; i++ )
            {
                chkBox[i].checked = 0;
            }
            nData = 0;
        }
    }

//-->
</script>

<input type='button' name='btn' value='S' class='inputbtn' onClick='selectAll(this)' />