Sample REST api call for SharePoint-Hosted app

sp2013_SampleREST

    $.ajax(
        {
            url: _spPageContextInfo.webServerRelativeUrl + "/_api/web/currentuser",
            type: "GET",
            headers: {
                "accept": "application/json;odata=verbose",
            },
            success: function (data) {
                $("#message").text('Hello ' + data.d.Title);
            },
            error: function (err) {
                alert(JSON.stringify(err));
            }
        });