Analysis of the cache problem of IE for AJAX request result _ajax related

By default, IE caches the results of the AJAX request for the request address. In other words, before the cache expires, multiple AJAX requests for the same address are actually sent to the server for the first time. In some cases, this default caching mechanism is not what we want (such as getting real-time data), this article simply discusses the problem and introduces several solutions.

Directory

I. Recurring problems

Second, to solve the problem by adding a suffix to the URL address

Third, through jquery Ajax settings to solve the problem

Iv. Solving problems by customizing responses

I. Recurring problems

We use a asp.net MVC application to reproduce IE caching for AJAX request results. In an empty asp.net MVC application we defined the following default HomeController, which contains an action method getcurrenttime that returns the current time.

 public class HomeController Controller
 {public
  actionresult Index ()
  {return
   View ();
  }
  
  public string GetCurrentTime ()
  {return
   DateTime.Now.ToLongTimeString ();
  }
 }

The default action method index corresponds to the view definition as follows. We use the JQuery method to invoke the GetCurrentTime operation in Ajax mode every 5 seconds and display the returned results.

<! DOCTYPE html>
  
 

Running the program in a different browser results in different output, as shown in the following illustration, the Chrome browser can display real-time time, but the time displayed in IE is the same.

Second, to solve the problem by adding a suffix to the URL address

Because the result of IE's return for AJAX requests is cached based on the request address, if you do not want the caching mechanism to take effect, we can resolve the problem by adding a different suffix to the request address on each request. For this example, we use the following code to add a query string based on the current time for the request address, and then run the program again, IE will display the real-time time.

 <! DOCTYPE html>
  
 

Third, through jquery Ajax settings to solve the problem

In fact, jquery has an AJAX setting for this, and we just need to call the $.ajaxsetup method in the following way to disable the Ajaz caching mechanism.

 <! DOCTYPE html>
  
 

In fact, this mechanism of jquery is also implemented by adding a different query string suffix to the request address, which can be confirmed by a fiddler interception request.

Iv. Solving problems by customizing responses

We can control the browser's caching of results by responding to the request, and we have defined the following as a actionfilter named Nocacheattribute. In the onactionexecuted method of implementation, we call the current HttpResponse SetCacheability method to set the cache option to NoCache. After the Nocacheattribute feature is applied to the GetCurrentTime method, running our program can still get real-time time in IE.

public class HomeController Controller
 {public
  actionresult Index ()
  {return
   View ();
  }
  
  [NoCache] 
  public string GetCurrentTime ()
  {return
   DateTime.Now.ToLongTimeString ();
  }
 }
 public class Nocacheattribute FilterAttribute, Iactionfilter
 {public
  void onactionexecuted ( ActionExecutedContext filtercontext)
  {
   filterContext.HttpContext.Response.Cache.SetCacheability ( Httpcacheability.nocache);
  }
 
  public void onactionexecuting (ActionExecutingContext filtercontext)
  {}
 }

The actual Nocacheattribute attribute ultimately controls the Cache-control header of the message message and sets it to "No-cache", which instructs the browser not to cache the results. The response message for the GetCurrentTime request is shown below:

 http/. OK
 Server asp.net Development server/
 ... Date Thu, X-aspnet-version GMT
 .
 X-aspnetmvc-version.
 Cache-control no-cache 
 Pragma no-cache
 Expires-Content-type text/html
 ;
 charset=utf- Content-length 
 Connection Close
 PM