javascript - jquery touchwipe how to get $(this)

I am using the jquery touchwipe plugin on my scroll list, and i can't get
attribute from $(this).I want to use $(this) to get its children elment class="t7 edit" and add class 'show' to it.Does anyone know how to fix it?

html:

script code:

var $main_list_wrapper = $("#main_list_wrapper").find('.item');

$main_list_wrapper.touchwipe({
    preventDefaultEvents: false,
    wipeLeft: function() { 

        $(this).find('.t8.cancel').removeClass('show');
        $(this).find('.t7.edit').removeClass('show');
        var thisclass = $(this).attr('class');
        alert(thisclass);
        return false;
    },
    wipeRight: function() { 
        $sb(this).find('.t8.cancel').addClass('show');
        $sb(this).find('.t7.edit').addClass('show');
        return false;

    }
});

Like alert(thisclass). It shows "undefine".

---

Thank you all.my friend write this to me, and it work!

$main_list_wrapper.each(function () {
    var $this = $sb(this);

    $this.touchwipe({
        preventDefaultEvents: false,
        wipeLeft: function() { 
            var $pcs = $this;
            $pcs.find('.t8').removeClass('show');
            $pcs.find('.t7').removeClass('show');
            return false;

        },
        wipeRight: function() { 
            var $pcs = $this;
            $pcs.find('.t8').addClass('show');
            $pcs.find('.t7').addClass('show');
            return false;
        }
    });
});