A very simple filter intended for use with AngularJS's `ng-repeat`, etc. to use only unique array items.

README.md

I wrote this for a project that didn't want to import additional libraries just for this functionality.
It could probably be more efficient and it only supports direct attributes of the item in question.
It would be nice to add support for attr.subattr.etc at some point. (Maybe using AngularJS's $parse()?)

Other similar functions:

• lodash.js' (successor to underscore.js) _.uniqBy() or _.uniqWith(): https://lodash.com/docs
• "Standard" JS' own Array.reduce() method, as explained by: http://elijahmanor.com/reducing-filter-and-map-down-to-reduce/
• angular-filter's uniq or unique filter: https://github.com/a8m/angular-filter

angular_unique_filter.js

angular.module('myFilters', [])
  .filter('unique', function () {
    return function (items, attr) {
      var seen = {};
      return items.filter(function (item) {
        return (angular.isUndefined(attr) || !item.hasOwnProperty(attr))
          ? true
          : seen[item[attr]] = !seen[item[attr]];
      });
    };
  });