force reload/refresh a second webpage through php

Question

I'm trying to force to reload a (second) page if a criteria is met in php But if the criteria is met, i want the page to force reload everywhere, even if 10 people have it open at once for example.

for simplicty lets say the code is like this:

in /filelocation/script.php:

if {$data == "ok"}{
reload/refresh "reload.php" if it's open somewhere;
}

I came across a software that basicly does this, and i want to understand how this is done. (it works cross device somehow, so i asume its done through php somehow)

question from:https://stackoverflow.com/questions/65842118/force-reload-refresh-a-second-webpage-through-php

Answer 1

Well, in your PHP code, you cannot simply reload/refresh something for all the users connected. This is simply because the PHP code is only executed when your browser requests a page on the server so it's only executed to build the HTML response and then it stops executing. Once the browser has the HTML response it will render the page and then it waits for an action from the user to do something else (such as clicking on a link or posting a form).

I imagine that you would like that when a specific user does something, like posting a comment or buying a product, you would like all the other visitors to be notified that a new comment has been posted or that the number of products available has been reduced.

To do that, you need to implement some JavaScript which is executed in the browser of each visitor. The idea is to keep a connection with the server with the help of web sockets. This way, you can inform the browser that something has changed.

You could google to find some examples of PHP apps using web sockets. The first example I found:

• https://www.twilio.com/blog/create-php-websocket-server-build-real-time-even-driven-application

Another solution could be to have some JavaScript doing some pooling, meaning that every N seconds, it executes an Ajax request to the server to ask if something has changed. This can be done with the help of setTimeout(yourFunction, 10000) to call a JavaScript function every 10 seconds. This function will do the Ajax request and then update the part of your page that needs to change. Just be carefull that if you get a lot of users on your site then you'll produce quite a lot of load on your server. So this wouldn't be a good solution, but it could be an alternative to the web sockets.