javascript in and filter_keys

gistfile1

        var __in__ = function(elem, array){
            array.forEach(function(item) {
                if (item === elem) return true;
            });
            return false;
        };

        var __filter_keys = function(obj, filter) {
            var result = {};
            var extraKeys = $.grep(Object.keys(obj), function(el, i) {
                return !(__in__(el, filter));
            });

            if (extraKeys.length > 0) {
                extraKeys.forEach(function(key) {
                    result[key]=obj[key];
                });
            }
            return result;
        };