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Ajax won't work for content change

Asked by duncanb7

at 2024-11-18 12:07:12

Point:500 Replies:16 POST_ID:828430USER_ID:11059

Topic:

Asynchronous Javascript and XML (AJAX);Hypertext Markup Language (HTML);JavaScript

Recently I am doing Ajax tutorial from http://www.w3schools.com/ajax/tryit.asp?filename=tryajax_first
and i found my IE7 window with the code is not reacted to the content change of the txt file I made
that is supposed to be opened by Ajax code for data update, I try it many time for clicking button
to load ajax function & always display the previous content of the file until I quit IE7 window and
restart IE7 again OR I go to web the txt file once directly in IE7 and then run the code again , after doing that,
the content change is reacted. So I go to swtich to IE6 XP in other computer , it also have same problem.
That is big problem for me to go ahead to use Mootools library or contiune Ajax data update works

Please Advise, and if possible run it at your side and test it
If you "NOT" understand my question, please don't hesitate to let me know

Recently I found a lot of content "NOT" change issue by Ajax when using mootools library so that
is why I go back to fundumental debugging check with the tutorial again. It seems it is not
virus issue since both IE7 and IE6 computer also the same issue Probably it is xmlhttp open file issue
with reload or refresh .

Duncan

html><head><script type="text/javascript">function loadXMLDoc(){if (window.XMLHttpRequest)  {// code for IE7+, Firefox, Chrome, Opera, Safari  xmlhttp=new XMLHttpRequest();alert("IE7+");  }else  {// code for IE6, IE5  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");alert("IE6-5");  }xmlhttp.onreadystatechange=function()  {  if (xmlhttp.readyState==4 && xmlhttp.status==200)    {    document.getElementById("myDiv").innerHTML=xmlhttp.responseText;    }  }xmlhttp.open("GET","http://www.mywebsite.com/ajax_info.txt",true);xmlhttp.send();}</script></head><body><div id="myDiv"><h2>Let AJAX change this text</h2></div><button type="button" onclick="loadXMLDoc()">Change Content</button></body></html>

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Attachment:ajax-info.txt

Author: duncanb7 replied at 2024-11-19 04:43:34

Q1) Underscores are fine to use as are dashes, what @armchang is saying is that the filename is different to the one you were trying to load. ajax-info.txt is different to ajax_info.txt

Q2) That's right though i'm not sure that would work 100% of the time because the url never changes, which is why i suggested you put the current time on the end of the url as it makes each and every ajax call unique

Q3) putting ? at the end of the url is saying to the server that you are sending some variables and information. it will always load ajax_infor.txt. Because ajax_infor.txt is not a script the variables/information is not processed. If you instead used a server side script such as PHP or ASP then in that script you could access the variables and do something with them. It is not relevant in your case and it is only used to fool IE into not caching the data

Expert: _alias99 replied at 2024-11-19 04:15:32

Reopened per Author's request:
http://www.experts-exchange.com/Community_Support/General/Q_26625514.html

_alias99
Community Support Moderator

Expert: Rob Jurd replied at 2024-11-18 17:10:58

Author: duncanb7 replied at 2024-11-18 16:45:35

Solution-1, forget to tell you, xmlhttp.open("GET","http://localhost/screen_update/sales1.htm?ignoreMe"+new Date().getTime(),true); that also work for me already.

Solution-2, it works after back put var to count=count+1, i.e var count=count+1 with your last version code

COuld you answer me the following before closing this thread.

Qusetion-1, don't user underscore in the future for filename or doesn't care ?
QUestion-2, how it works in Solution-2, let me try to mention it, use the new URL = ajax_info.txt?%load=1 to cheat
IE not cache memory in my PC and go to load the new url
Question-3 Why URL in internet will treat ajax_info.txt 's IP address same as ajax_infor.txt?load=1 becuae
putting "?" inside so ingore other char. OR when internet could not find out ajax_infor.txt?load=1 in mywbeiste
, it will change it to closer one , ajax_info.txt . Please advise

Expert: armchang replied at 2024-11-18 16:37:45

Yes. I've also applied to his code, one which works to his requirements and it makes that a bit different.

Expert: Rob Jurd replied at 2024-11-18 16:10:23

so @armchang is really doing the same thing as i've posted above:

http://www.experts-exchange.com/Programming/Languages/Scripting/AJAX/Q_26625196.html?cid=1573#a34168243

Assisted Solution

Expert: armchang replied at 2024-11-18 15:10:54

120 points EXCELLENT

Hi Duncanb7,

After a long try, it's finally done. I've modified your code to accomodate cache problem from IE. The code appends the "?loaded=<counter>" into the location of the .txt file so that IE always reload the new contents and it works! I've tried using the setRequestHeader() solution but no luck there. So try the code:

<html><head><script type="text/javascript">url = "?loaded=";counter = 0;function loadXMLDoc(url){if (window.XMLHttpRequest)  {// code for IE7+, Firefox, Chrome, Opera, Safari  xmlhttp=new XMLHttpRequest();alert("IE7+");  }else  {// code for IE6, IE5  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");alert("IE6-5");  }xmlhttp.onreadystatechange=function()  {  if (xmlhttp.readyState==4 && xmlhttp.status==200)    {    document.getElementById("myDiv").innerHTML=xmlhttp.responseText;    }  }xmlhttp.open("GET","ajax-info.txt"+url,true);xmlhttp.setRequestHeader("Cache-Control", "no-cache");xmlhttp.send();counter = counter+1;}function getUrl(){	return url+counter.toString();}</script></head><body><div id="myDiv"><h2>Let AJAX change this text</h2></div><button type="button" onclick="loadXMLDoc(getUrl());">Change Content</button>

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Expert: Rob Jurd replied at 2024-11-18 14:10:57

Author would like to keep the question open

Author: duncanb7 replied at 2024-11-18 13:55:33

Dear EE-Adm

I click wrong button, please help to re-open this thread for re-credit process

Duncan

Author: duncanb7 replied at 2024-11-18 13:43:19

The question is

1- Don't use underscore for file name in future, RIght ? What is harmful using underscore in filename

I will ask you later onfor cache topic that is interesting, I also experience a lot of issue like using reload
button

Thanks

DUncan

Assisted Solution

Expert: armchang replied at 2024-11-18 13:40:42

30 points EXCELLENT

Oh,

One thing, I've experienced is that. If you want to force to load/refresh the page with new settings from javascript, you can append into the url string a ?load=1. This is only applicable if you have new changes from your page i.e. you can skip this if you're already done with your code and never have to refresh your code changes.

Expert: Rob Jurd replied at 2024-11-18 13:30:54

Cache is just a copy of something you have already downloaded. it is used to save time downloading it again. if you keep calling the same url using ajax then internet explorer thinks you're downloading the same thing again and won't do it. you need to force IE to download it by making the url unique and you do that by adding the time to the end of the request

Expert: armchang replied at 2024-11-18 13:27:32

Hi,

I've found out what's causing you your trouble. All of the code you posted works just that you have to refer to the correct file/ filename, i.e. you should change:

http://www.mywebsite.com/ajax_info.txt --> http://www.mywebsite.com/ajax-info.txt

I've traced your code and if it can't find the file it will not get inside readystatechange. So please check if your filename is correct. Note the underscores and dashes.

Author: duncanb7 replied at 2024-11-18 13:26:53

You always say cache, I dont' understand it , just know cache memory on computer
What does it imply in AJax.

I will try the code

Expert: Rob Jurd replied at 2024-11-18 13:19:54

and this works for me in Internet Explorer and Firefox

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head><title></title><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><link rel="stylesheet" type="text/css" media="screen" href="?" /><meta name="author" content="?" /><meta name="Keywords" content="?" /><meta name="Description" content="?" /><script type="text/javascript"><!--function loadXMLDoc(){if (window.XMLHttpRequest)  {// code for IE7+, Firefox, Chrome, Opera, Safari  xmlhttp=new XMLHttpRequest();alert("IE7+, Firefox, Chrome, Opera, Safari");  }else  {// code for IE6, IE5  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");alert("IE6-5");  }xmlhttp.onreadystatechange=function()  {  if (xmlhttp.readyState==4 && xmlhttp.status==200)    {    document.getElementById("myDiv").innerHTML=xmlhttp.responseText;    }  }xmlhttp.open("GET","http://localhost/screen_update/sales1.htm?ignoreMe"+new Date().getTime(),true);xmlhttp.send();}--></script><link rel="shortcut icon" href="http://?.ico" /></head><body><button type="button" onclick="loadXMLDoc()">Change Content</button><div id="myDiv"><h2>Let AJAX change this text</h2></div></body></html>

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Accepted Solution

Expert: Rob Jurd replied at 2024-11-18 13:19:33

350 points EXCELLENT

Duncan,

Internet Explorer caches the ajax requests, MEANING it thinks your just getting the same thing again and won't update your webpage. so to fix it using the code above you will need to change the following line :

xmlhttp.open("GET","http://www.mywebsite.com/ajax_info.txt",true);

to

xmlhttp.open("GET","http://www.mywebsite.com/ajax_info.txt?ignoreMe"+new Date().getTime(),true);

&nbps;

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