根据对Mysql Records计数的更改执行脚本

How do I execute a script based on a change to the total count of records in a mysql table. div1 echoes the amount of records in a table just fine. Using the .load ajax request, the div is constantly refreshed every 0,5 second so it'll always know how many records there are almost real-time.

 <div class="div1"> 
            <?php $row_cnt = mysqli_num_rows($result);   
            echo "table has $row_cnt records" ; ?>                  
 </div>

 <script>
    function refreshdiv(){
        $('.div1').load('backendform.php',function () {
             $(this).unwrap();
        });
    }
    refreshdiv();
    setInterval(function(){
        refreshdiv();
    }, 500);
</script>

Here I'm trying to figure out how to call a JS function when the count has changed within the last minute (or second, doesn't matter). So if $row_cnt has for example changed from outputting 5 to 6, how do I trigger the execution for this statement?

<?php
//if record was added in last minute
if($row_cnt...)
echo '<script type="text/javascript">',
     'notification();',
     '</script>'
;?>
<script>

I suppose what also could work is if I could tell if a record has been added to the Mysql table within the last few seconds. Each record has a timestamp. But I don't even know if this can be done because I found no similar questions on SO.

You can set data for #div1 like data-row

<?php $row_cnt = mysqli_num_rows( $result ); ?>
<div class="div1" data-row="<?php echo $row_cnt ?>">
    <?php echo "table has $row_cnt records"; ?>
</div>

put notification function in setInterval and use #div1 data-row to compare:

<script>
    function refreshdiv() {
        $('.div1').load('backendform.php', function () {
            $(this).unwrap();
        });
    }
    refreshdiv();
    function notification() {
        var row = $('.div1').attr('data-row');
        if (row == 2) {
            //do something
        }
        else{
            //do something
        }
    }
    setInterval(function () {
        refreshdiv();
        notification();
    }, 500);
</script>