问需要在所有ajax和jquery post函数之前调用一个javascript函数

EN

        /***
         * Global Ajax call which gets excuted before each $.ajax and $.post function
         * at server side chk session is set or destroy 
         ***/
        $(document).on('ajaxStart', function()
        {
            $.post( BASEURL+"/login/chkLogin",
            {},
            function(data)
            {
                if (data == 'login') {
                  window.location = BASE_URL+'/login'; //Load the login page
                }
                else
                {
                    //alert('all okay! go and execute!'); 
                    //No need to write anything in else part 
                    //or can say no need of else block 
                    //if all okay normal ajax action is processed
                }
            });     
      });

$.ajax({
   beforeSend: function(){
     // Handle the beforeSend event
   },
   complete: function(){
     // Handle the complete event
   }
   // ......
 });

$(document).on('ajaxError', function(el, xhr) {
    if (xhr.status == 401) {
        alert('Unauthorized');
    }
});