Ajax to implement server and browser long connection function _ajax related

Sometimes, you need the server to actively push data to the browser, here with Ajax to achieve this function, specifically, see here:

<script type= "Text/javascript" src= "__css__/bootstrap-3.3.5-dist/js/bootstrap.min.js" ></script> <
  Script type= "Text/javascript" > var uid = "{$uid}";
  var i = 0;
  var timer; $ (). Ready (function () {//Open Sweep code login modal box $ (' #login '). Click (function () {//If user is logged in, return if (UID) {retur
      n;
    }//Open modal box, load data from remote by remotely option $ (' #loginModel '). Modal ({remote: "{: U (' User/login ')}"});
     
    });
    Empty the data after the modal box is hidden $ ("#loginModel"). On (' Hidden.bs.modal ', function () {$ (this). Removedata ("Bs.modal");
     
    }); When the modal box is displayed, the timer is requested to server $ (' #loginModel ') once every three seconds, by returning it periodically to request the data. On (' Shown.bs.modal ', function (e) {timer = Setinter
    Val (Ajax_request, 3000);
  });
   
  });
    Ajax request functions, function ajax_request () {i++; If you have requested 20 this does not request success, then force the end, give the hint information, because every 3s call once, for 20 times, is about a minute of the time if (i >) {$ ('. Login_info1 '). html (' <span style = "color:red;"
      > Login timeout, please refresh the page if required ~</span> '); Clearinterval (TimeR);
    return; } $.ajax ({type: "post", url: "{: U (' User/login_qrcode ')}", timeout:3000, data: {"Scen E_ID ": $ (' #scene_id '). Val ()}, Success:function (msg) {if (1 = msg.status) {$ ('. Login_inf O1 '). html (' <span style= ' color: #0C9; "
          > ' +msg.info+ ' </span> ');
          SetTimeout (refresh, 3000);
        return;
  }}, Error:function () {}});
  }//Overloaded page function refresh () {location.reload (); } </script>

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