collections-add-delete-links.js

$(function(){
    var addLink = $('<button type="button" class="btn btn-info add"><i class="icon icon-plus icon-white"></i></button>');
    var deleteLink = $('<button type="button" class="btn btn-danger remove"><i class="icon icon-trash icon-white"></i></button>');

    function addLinkClick(e) {
        e.preventDefault();

        var collection = $(this).closest(".collection-allow-add");

        var index = 1+ collection.data("index");

        var prototype = collection.data("prototype").replace(/__name__label__/g, index).replace(/__name__/g, index);
        prototype = $(prototype);

        if (collection.hasClass("collection-allow-delete")) {
            prototype.append(deleteLink.clone().click(deleteLinkClick));
        }

        collection.data("index", index);
        collection.children(".controls").append(prototype);
    }

    function deleteLinkClick(e) {
        e.preventDefault();
        $(this).parent().remove();
    }

    $("form .collection-allow-delete").each(function(){
        $("> .controls > .collection-item", this).append(deleteLink.clone().click(deleteLinkClick));
    });

    $("form .collection-allow-add").each(function(){
        if (!$(this).data("prototype").length) return;

        $(this).data("index", $(this).children().length);

        addLink.click(addLinkClick);
        $(this).append(addLink);
    });
});