利用filter过滤去重

1     var r,
2     ary = ['apple', 'strawberry', 'banana', 'pear', 'apple', 'orange', 'orange', 'strawberry'];
3     r = ary.filter(function (currentValue, index, arr) {
4        return  arr.indexOf(currentValue) === index;
5      });
6  　　console.log(r.toString());