1Array.prototype.getDuplicates = function () {
2 var duplicates = {};
3 for (var i = 0; i < this.length; i++) {
4 if(duplicates.hasOwnProperty(this[i])) {
5 duplicates[this[i]].push(i);
6 } else if (this.lastIndexOf(this[i]) !== i) {
7 duplicates[this[i]] = [i];
8 }
9 }
10
11 return duplicates;
12};