function filter(type) {
        $.getJSON('/activity_stream/global-activity-stream/', {xhr: "true", filter: type},
        function(data) {
    $('.mainContent').children().remove();
    $(data).appendTo('.mainContent');
    });
}

$(".btn").click(function () {
filter("recent");
});

$( '.my-selector' )

$( [ 'my-data' ] )