Sys.Application.add_init(appl_init);

function appl_init() {
    var pgRegMgr = Sys.WebForms.PageRequestManager.getInstance();

    pgRegMgr.add_pageLoaded(function () {

        (function (d) {
            var js, id = 'facebook-jssdk'; if (d.getElementById(id)) { return; }
            js = d.createElement('script'); js.id = id; js.async = true;
            js.src = "http://connect.facebook.net/en_US/all.js#xfbml=1";
            d.getElementsByTagName('head')[0].appendChild(js);
        } (document));
    });


}