AngularedCollectionController.js

sciApp.controller('AngularedCollectionController', ['$scope', '$compile', function ($scope, $compile) {
    $scope.index = 1;

    $scope.init = function (collectionId) {
        var indexes = [];

        $('#' + collectionId).find('input[type=hidden]').each(function () {
            var attrName = $(this).attr('name');

            var indexFinder = new RegExp('\\]\\[(\\d+)\\]\\[');
            var finded = indexFinder.exec(attrName);

            if (finded.length > 1) {
                indexes.push(parseInt(finded[1]));
            }
        });

        if (indexes.length > 0) {
            $scope.index = Math.max.apply(Math, indexes) + 1;
        } else {
            $scope.index = 1;
        }
    };

    $scope.add = function (event) {
        var $collectionItems = $(event.target).parent().find('div.collection-items');
        var prototype = $collectionItems.attr('data-prototype');
        var prototypeName = $collectionItems.attr('data-prototype-name');
        var prototypeLabel = $collectionItems.attr('data-prototype-label');

        // Just in case it doesn't get it
        if (typeof prototypeName === 'undefined') {
            prototypeName = '__name__';
        }

        if (typeof prototypeLabel === 'undefined') {
            prototypeLabelss = '__name__label__';
        }

        var nameReplacePattern = new RegExp(prototypeName, 'g');
        var labelReplacePattern = new RegExp(prototypeLabel, 'g');

        prototype = prototype.replace(labelReplacePattern, $scope.index)
            .replace(nameReplacePattern, $scope.index);

        $newCollectionItem = $compile(prototype)($scope);
        $collectionItems.append($newCollectionItem);

        $scope.index++;
    };
}]);

fields.html.twig

{% block angulared_collection_widget %}
    {% set randomCollectionId = 'collection' ~ random() ~ random() ~ random() %}
    <div id="{{ randomCollectionId }}" ng-init="init('{{ randomCollectionId }}')" ng-controller="AngularedCollectionController">
        {% spaceless %}
            {% if prototype is defined %}
                {% set prototype_markup = form_row(prototype) %}
                {% set data_prototype_name = form.vars.form.vars.prototype.vars.name|default('__name__') %}
                {% set data_prototype_label = form.vars.form.vars.prototype.vars.label|default('__name__label__') %}
                {% set widget_form_group_attr = widget_form_group_attr|merge({
                'data-prototype': prototype_markup,
                'data-prototype-name': data_prototype_name,
                'data-prototype-label': data_prototype_label
                })|merge(attr) %}
            {% endif %}
            {# Add row by default use attr.class to change#}
            {% if 'collection' in form.vars.block_prefixes and attr.class is defined %}
                {% set widget_form_group_attr = widget_form_group_attr|merge({'class': widget_form_group_attr.class|default('row') ~ ' ' ~ attr.class}) %}
            {% endif %}
            {# collection item adds class {form_id}_form-group  too #}
            {% set widget_form_group_attr = widget_form_group_attr|merge({'id': 'collection' ~ id ~ '_form_group', 'class': widget_form_group_attr.class ~ ' collection-items ' ~ id ~ '_form_group'}) %}

            <div {% for attrname,attrvalue in widget_form_group_attr %} {{attrname}}="{{attrvalue}}"{% endfor %}>
            {# Add initial prototype form #}
            {% if form.vars.value|length == 0 and prototype is defined %}
                {% for name in prototype_names %}
                    {{ prototype_markup|replace({'__name__': name})|raw }}
                {% endfor %}
            {% endif %}
            {{ block('form_widget') }}
            </div>
        {% endspaceless %}

        <a {% for attrname,attrvalue in widget_add_btn.attr %} {{attrname}}="{{attrvalue}}"{% endfor %} ng-click="add($event)">
            {% if widget_add_btn.icon is not null %}
                {{ mopa_bootstrap_icon(widget_add_btn.icon, widget_add_btn.icon_inverted|default(false)) }}
            {% endif %}
            {{ widget_add_btn.label|trans({}, translation_domain) }}
        </a>
    </div>
{% endblock angulared_collection_widget %}