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PHP / JQuery refresh content

Anonymous Thu 20 Nov 2025 10:22:49 No.1549319 View View Reply Original Report

I'm making a chat app but it still needs one thing.
It updates the messages every x seconds, but I need to make it so that it only checks for new messages every x seconds and only refreshes the post area div if there is new content.
How do I achieve dat?

For some reason the "textstatus notmodified" thing doesn't work.
mail_getposts.php contains a while loop that fetches posts from the SQL table.

Anonymous

Anonymous Thu 20 Nov 2025 17:16:51 No.1549337 Report

Quoted By: >>1549338 >>1549497 >>1549500 >>1549742

>>1549319
i think that the "textstatus notmodified", refers to headers which are said from server when it's sending cache header and Last-Modified or ETag headers.
refer to ifModified in https://api.jquery.com/jquery.ajax/
On its own it doesn't know the page that is sent is different, you would need to set appropriate headers in the php script, for that you would need to have server side logic, which would remember what was already sent which is imho quite complicated
The best would imho be to send new messages in json, and append them client side (that would make easy knowing stuff like timestamp of last message)
if you insist on keep doing it with sending html, instead of refreshing with new content, first load existing messages and then have different php script with timestamp argument which is asked every X seconds if there were any new messages in last X seconds (i.e. newer than current time - X seconds) and if there are any, append them to the #postarea instead of replacing it (though with sending html without parsing it client side, you risk having duplicate or missed messages if they come near the X second threshold)

Anonymous

Anonymous Thu 20 Nov 2025 17:29:12 No.1549338 Report

Quoted By:

>>1549337
>for that you would need to have server side logic, which would remember what was already sent which is imho quite complicated
nevermind, that's stupid
on second thought you can probably just set Last-Modified header to timestamp of last message

Anonymous

Anonymous Sat 22 Nov 2025 12:07:28 No.1549497 Report

Quoted By:

>>1549337
I dunno how to implement that bro

Anonymous

Anonymous Sat 22 Nov 2025 12:57:53 No.1549500 Report

Quoted By:

>>1549337
https://stackoverflow.com/questions/13578579/refresh-div-but-only-if-there-is-new-content-from-php-file?rq=1

You mean like the first answer in this thread?

Anonymous

Anonymous Sat 22 Nov 2025 20:05:37 No.1549522 Report

Quoted By: >>1549526

Considering you're using SQL, cant u just do some super simple and retarded shit like, when you load the page, you get the timestamp of the latest message and store it somewhere, like a PHP variable or whatever.
Then every x seconds you send a request to the database checking for new messages and if there is a new message then you reload the .div

I'm not a CS engineer and this might be horribly optimized. You'll literally ping the database all teh fucking time.

Anonymous

Anonymous Sat 22 Nov 2025 21:11:52 No.1549526 Report

Quoted By: >>1549551

>>1549522
Yeah but how do I compare data in PHP variables when the comparing / page refreshing function is in Jquery/Ajax?

Anonymous

Anonymous Sun 23 Nov 2025 02:28:09 No.1549551 Report

Quoted By: >>1549597

>>1549526
From ajax, you could do something like GET mail_getposts.php&lastMessageTimestamp=123, and in PHP you could do select * from messages where ....... and created_at > :lastMessageTimestamp order by .....
This will give you an empty result when there are no new posts.
On success in ajax do something like function(data) {if data.trim() !== 0 {
// reload the #postarea
}
// else do nothing
}

The If-Modified-Since header and the Not Modified HTTP response are for systems with caching systems, so I wouldn't use those for this.

Anonymous

View Same Google ImgOps iqdb SauceNAO Screenshot from 2025-11-23 13-05 (...).png, 54KiB, 1374x432

Anonymous Sun 23 Nov 2025 11:06:32 No.1549597 Report

Quoted By: >>1549615 >>1549621

>>1549551

I think at this point my main issue might be my page structure and understanding GET.
Should I be ajaxgetting the file with the SQL queries? I have them in a different file (picrel).
mail.php has the main structure of the page and these ajax scripts
mail_getposts.php has the sql preparations

>url: "mail_getposts.php?lastTimeStamp=something",
With this in the code, it doesn't do anything.

>url: "mail.php?lastTimeStamp=something",
With this, it updates the post area content at regular intervals indefinitely regardless of whether something has happened or not.
Maybe it's because it's the same page that houses the script itself?

Anonymous

Anonymous Sun 23 Nov 2025 17:55:26 No.1549615 Report

Quoted By: >>1549621 >>1549711

>>1549597
OP here again.
I found a tutorial project that does exactly what I want to do.

https://www.phpzag.com/build-live-chat-system-with-ajax-php-mysql/

That's like a full-on Discord with PHP which is what I'm trying to make.
But the problem is the usual: the tutorial is so extensive that I can't just snatch one line of code from it and inject it into my own code.
I'd have to entirely rebuild my own code to match the tutorial, or take the tutorial as my starting point and shape it to look like my existing project.
I think both options are bad because I want my code to be unique. The saddest way to implement something is to take a tutorial, change the variable names, and just adjust the CSS. That's basically just a fan mod of the original.

Anonymous

View Same Google ImgOps iqdb SauceNAO 1756361661641174.png, 22KiB, 723x283

Anonymous Sun 23 Nov 2025 18:48:37 No.1549621 Report

Quoted By:

>>1549597
>url: "mail_getposts.php?lastTimeStamp=something",
That's not how you do it, you add it to the data attribute of ajax as key-value pairs. `"mail_getposts.php?lastTimeStamp=something"` is just what gets sent actually. You will be able to access $_GET["lastTimestamp"] in php like you wrote on line 7.
As for the query, you should only use prepared statements, so none of the shit on line 9, and you don't concatenate stuff into a prepared statement like you did on line 11. Look into this: https://www.w3schools.com/php/php_mysql_prepared_statements.asp
So when you pass ANYTHING to mysqli, you always do it through a prepared statement, not using . to put the strings together.
>>1549615
This tutorial's code isn't supposed to be like this either, holy shit. This is what gave PHP a bad rep.

Anonymous

Anonymous Sun 23 Nov 2025 23:05:16 No.1549640 Report

Quoted By: >>1549659

I feel like there are several syntaxes within PHP
Sometimes I see "normal" PHP and then someone throws me this weird-ass PHP with arrows ->

Anonymous

Anonymous Mon 24 Nov 2025 03:02:38 No.1549659 Report

Quoted By:

>>1549640
>weird-ass PHP with arrows ->
That's used with PHP objects.
You can use mysqli in procedural mode and object oriented mode. They both do the same thing but wiwth a different syntax: https://www.php.net/manual/en/mysqli.prepare.php
It's ok to use either one.

Anonymous

Anonymous Mon 24 Nov 2025 17:51:36 No.1549711 Report

Quoted By:

>>1549615
>https://www.phpzag.com/build-live-chat-system-with-ajax-php-mysql/

I think this code just updates the message fetching function every 5 seconds and doesn't actually check the database or do anything like that.

Anonymous

Anonymous Mon 24 Nov 2025 23:05:35 No.1549742 Report

Quoted By: >>1549813

>>1549337
>then have different php script with timestamp argument which is asked every X seconds if there were any new messages in last X seconds (i.e. newer than current time - X seconds) and if there are any, append them to the #postarea instead of replacing it (though with sending html without parsing it client side, you risk having duplicate or missed messages if they come near the X second threshold)

OP here.
I did this, with hours of work I actually got it to work. Except that it doesn't. For the longest time I couldn't figure out why it worked with any other argument except for timestamps.
Then I realized the issue. Every time I hit enter and send a new message, the whole page gets reloaded. This also reloads the script that generates the test timestamp which ruins it.
There is never a situation where the database has a message with a fresher timestamp than the script-generated timestamp.
Simply put: this approach only works if I somehow get rid of the pageload. Meaning I have to figure out a whole new way of submitting messages in the first place.

Anonymous

Anonymous Tue 25 Nov 2025 11:42:10 No.1549813 Report

Quoted By: >>1549844

>>1549742
I think the mistake is in generating a new timestamp when you do the check.
Literally get the timestamp from the latest message and store it somewhere like a PHP $_SESSION variable.
Then you compare this stored timestamp to what's in the database. If there's a message with a later timestamp, then you run the refresh function.

Anonymous

View Same Google ImgOps iqdb SauceNAO Screenshot from 2025-11-25 19-27 (...).png, 96KiB, 1242x691

Anonymous Tue 25 Nov 2025 18:02:12 No.1549844 Report

Quoted By:

>>1549813

OP here.
I finally got the fuckin' thing to work. Messages update nicely now.
The only downside is that I need to bombard the database every second checking for potential new messages
But it works.

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