查找数组中重复项的index

var ary = [5, 4, 4, 2, 7, 8, 33, 2222, 99, 88];

    function isRepeat(arr) {

        var hash = {};

        for (var i=0,len=arr.length;i<len;i++) {
            if (typeof hash[arr[i]]==‘undefined‘) {
                hash[arr[i]] = i;
            } else {
                console.log(i,hash[arr[i]]);
            }
        }

        return false;

    }


    isRepeat(ary);