var itemList = [{id:1, name:"A"}, {id:2, name:"B"}, {id:3, name:"C"}, {id:4, name:"D"}];

var _itmes = itemList.filter(function(item, index, array)
{
    console.log(this); <- "hello" String 객체
    return item.id > 2;
}, "hello");

_itmes
(2) [{…}, {…}]

예제)

isConfirmer : function()
{
    var _confirmer = this.domHost.acu.filter(function(item, index, array)
            {
                return item.awc_cnfm_id == this.domHost.sessionUser.usr_id;
            }, this);

    return _confirmer.length > 0;
},