Several solutions for AJAX suppression caching

The most common method is

Method 1: Server-side code joins

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Response.setheader ("Cache-control", "No-cache, must-revalidate");

Method 2: Use JavaScript to add a random number as a parameter in the URL in the AJAX submission.

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Req.open (url + "&" + math.random).

Cause: In IE, if the URL submitted by XMLHttpRequest is used in the same way as history, the cache is not submitted to the server at all. Therefore, the data that was just submitted cannot be fetched.

1. Add header ("Cache-control:no-cache, Must-revalidate") to the service end;(such as PHP)
2. Add Anyajaxobj.setrequestheader ("If-modified-since", "0") before Ajax sends the request;
3. Add Anyajaxobj.setrequestheader ("Cache-control", "No-cache") before the Ajax send request;
4. Add "fresh=" + math.random () after the Ajax URL parameter; Of course, the parameter fresh can be arbitrarily taken.
5. The fifth method is similar to the fourth, with the URL parameter followed by "? timestamp=" + New Date (). GetTime ();
6. Replace get with post: not recommended
Add a random number:

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Xmlhttp.open ("Get", "ajax.asp?now=" + New Date (). GetTime (), true);

Instance

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function Saveuserinfo () { Get the Accept return information layer var msg = document.getElementById ("msg"); Get form objects and user information values var f = document.user_info; var userName = F.user_name.value; var userage = F.user_age.value; var usersex = F.user_sex.value; Receive the URL address for the form var url = "/save_info.php"; The value of the post is required to join each variable by & var poststr = "User_name=" + userName + "&user_age=" + userage + "&user_sex=" + usersex; Instantiating Ajax var ajax = Initajax (); 　 To open a connection by post Ajax.open ("POST", url, True); Defines the transmitted file HTTP header information Ajax.setrequestheader ("Content-type", "application/x-www-form-urlencoded"); Send post data Ajax.send (POSTSTR); Get Execution status Ajax.onreadystatechange = function () { If the execution status succeeds, the return information is written to the specified layer if (ajax.readystate = = 4 && ajax.status = 200) { msg.innerhtml = Ajax.responsetext; } } }

Write a code that suppresses caching in an ASP page that you want to get asynchronously:

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Response.Buffer =true Response.ExpiresAbsolute =now ()-1 Response.expires=0 Response.cachecontrol= "No-cache"

Add Xmlhttp.setrequestheader ("If-modified-since", "0") before Ajax sends the request;

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Xmlhttp.open ("Get", URL, True); Xmlhttp.onreadystatechange = callhtml; Xmlhttp.setrequestheader ("If-modified-since", "0"); Xmlhttp.send ();

Ajax cache is maintained by the browser, for a url,ajax sent to the server only on the first request with the server interaction information, after the request, Ajax no longer submit requests to the server, but directly from the cache to extract data.

In some cases, we need to get updated data from the server each time. The idea is to make each request a different URL, without affecting the normal application: After the URL to add random content.

url=url+ "&" +math.random ();
1. Each request URL is different (Ajax cache will not work)
2. Does not affect the normal application (most basic)
To prevent caching in a JSP:

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Response.AddHeader ("Cache-control", "No-cache"); Response.AddHeader ("Expires", "Thu, 1970 00:00:01 GMT");

HTML Implementation method

/tbody>

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< META http-equiv= "Pragma" content= "No-cache" > <meta http-equiv= "Cache-control" content= "No-cache" Must-revalidate "> <meta http-equiv=" Expires "content=" Wed, Feb, 1997 08:21:57 GMT "