AngularJS Group By Directive without External Dependencies

This is a modification of Darryl’s solution above, that allows multiple group by parameters. In addition it makes use of $parse to allow the use of nested properties as group by parameters.

Example using multiple, nested parameters

http://jsfiddle.net/4Dpzj/6/

HTML

<h1>Multiple Grouping Parameters</h1>
<div ng-repeat="item in MyList  | orderBy:'groupfield' | groupBy:['groupfield', 'deep.category']">
    <h2 ng-show="item.group_by_CHANGED">{{item.groupfield}} {{item.deep.category}}</h2>
     <ul>
        <li>{{item.whatever}}</li>
     </ul>
</div>  

Filter (Javascript)

app.filter('groupBy', ['$parse', function ($parse) {
    return function (list, group_by) {

        var filtered = [];
        var prev_item = null;
        var group_changed = false;
        // this is a new field which is added to each item where we append "_CHANGED"
        // to indicate a field change in the list
        //was var new_field = group_by + '_CHANGED'; - JB 12/17/2013
        var new_field = 'group_by_CHANGED';

        // loop through each item in the list
        angular.forEach(list, function (item) {

            group_changed = false;

            // if not the first item
            if (prev_item !== null) {

                // check if any of the group by field changed

                //force group_by into Array
                group_by = angular.isArray(group_by) ? group_by : [group_by];

                //check each group by parameter
                for (var i = 0, len = group_by.length; i < len; i++) {
                    if ($parse(group_by[i])(prev_item) !== $parse(group_by[i])(item)) {
                        group_changed = true;
                    }
                }


            }// otherwise we have the first item in the list which is new
            else {
                group_changed = true;
            }

            // if the group changed, then add a new field to the item
            // to indicate this
            if (group_changed) {
                item[new_field] = true;
            } else {
                item[new_field] = false;
            }

            filtered.push(item);
            prev_item = item;

        });

        return filtered;
    };
}]);