<?php
$mysql_host='localhost';
$mysql_user='root';
$mysql_password='CAN'T KNOW MY PASWORD!!!1!';

mysql_connect($mysql_host,$mysql_user,$mysql_password);
@mysql_select_db('galaxall');
?>

<style>
.clap{
    background-color:red;
}





</style>






<p style="background-color:rgb(2,2,2)">
<div style="background-color:rgb(250,250,250);padding-bottom:3%;margin-right:20%">
<?php
$hello='hello everybody!!! &nbsp;&nbsp;&nbsp;&nbsp;I'm d boss!';
$img='<img src="b5.jpg">';


$query="SELECT * FROM `comments`  ";
$results = mysql_num_rows($query);

echo  $results;

if($is_query_run=mysql_query($query) )
{
$results = mysql_num_rows($is_query_run);

    echo "Number of comments:<font style='font-weight:bold;'>$results".'<p style="font-weight:bold;" onclick="alert("hello")">'.'</font>';

    while($query_execute=mysql_fetch_assoc($is_query_run) )
    {


        echo $query_execute ['Comment'].'<br>'.'<br>'.'<br>'."<a href='' class='clap'>.<img src='clap4.png' width='3%' height='3%'>.'&npsp;'.'&npsp;'.'&npsp;'.'&npsp;'.'&npsp;'
        .'Respond'</a>".'<p style="background-color:white;padding-bottom:1%;padding-left:3.5%;padding-top:1%;margin-left:0%;border:1px solid grey;border-radius:5%;box-shadow:2px 2px 2px #999;margin-right:25%; id="comment" >';




    }

}

    else
    {
        echo"Sorry, something went wrong...";
    }

?>
</p>

<script>

   var d = document.getElementsByClassName("clap");

   var c = document.getElementById("comment");

   function mouseOver() {
       d.style.backgroundColor = "red";
   }

   function mouseOut() {

       d.style.backgroundColor = "blue";
   }



   c.onmouseover = mouseOver();


   c.onmouseout = mouseOut();


</script>

10:45:19.526 comments_gxx58.php:50 Uncaught TypeError: Cannot set property 'backgroundColor' of undefined
    at mouseOver (comments_gxx58.php:50)
    at comments_gxx58.php:60