How to update content in a page using webhook?

I’m trying to update content in an active loaded page using webhook response.

Earlier, I used to trigger the function using setTimeout for every 5 secs but noticed its kind of increasing server load. So, now whenever there is a change on the database a webhook will be triggered through which I will update the content on the loaded page without refreshing it.

But how do I tell a webhook URL to change/update content on another page.?

so far code goes as :
PAGE#1:

<div id="loader_div">Some content</div>
<script>
function loadlink(){
    $('#loader_div').load('loading.php',function () {
         $(this).unwrap();
    });
}

loadlink(); // This will run on page load

setInterval(function(){
    loadlink() 
}, 5000); // this will run after every 5 seconds
</script>

loading.php

<p>some other content that i got from database</p>

Now the webhook URL is loading.php which gets the new update from the database, but how do I trigger the ‘loadlink();’ on the page1 without refreshing it and using set timeout..?

Please do not downvote the query, I’m trying my best to ask properly as per guidelines. You got to give time to rookies.

Any help is appreciated.