How to stop an ajax request

// Perform a simple Ajax request
var req = $.ajax({
  type: "GET",
  url: "/user/list/",
  success: function(data) {
    // Do something with the data...
    // Then remove the request.
    req = null;
  }
});

// Wait for 5 seconds
setTimeout(function(){
  // If the request is still running, abort it.
  if ( req ) req.abort();
}, 5000);