I'm using the following code lines in Javascript in order to return a value(String) from an AJAX response:
function ForumNameByForumID(ID) {
    var forum_name_topic_id = "";
    var params = JSON.stringify({ forumid: ID });
    $.ajax(
{
    type: "POST",
    dataType: "json",
    data: params,
    contentType: "application/json; charset=utf-8",
    url: "WebService1.asmx/ForumNameByForumID",
    success: function Process_Result(data) {
        forum_name_topic_id = data.d.toString();
    },
    error: function Process_Error() {  }
});
    return forum_name_topic_id;
}
but it returns an empty string..
