如何通过php中的按钮单击将AJAX信息传递给另一个用户？

Question

I want to implement AJAX to refresh the content automatically when there is new notification is incoming for the user.

---

Example for what I am trying to achieve:

user A sent a friend request to user B, so user B gets a notification, but the notification is only showing after the page is refreshed. I want to refresh the notification automatically, whenever the database is updated/inserted a new value.

AJAX:

$('#ajax').click(function(){
$(document).ready(function(){
$.ajax({
    type: 'POST',
    url:  '../main/count-fnd.php',
    success: function(data){
        $('#output').html(data);
    }
 });
});
});

Answer 1

To do it with AJAX (without using other technologies), the most used, rather the typical in these cases, is to use some kind of timer to refresh and check if there is any new notification every "x" seconds that you stipulate.

setInterval(() => {
    $.ajax({
       type: 'POST',
       url:  '../main/count-fnd.php',
       success: function(data){
           $('#output').html(data);
       }
    });
}, 5000); // refresh 5s