Highlighting text field when button is clicked

[ryanmetzler3]

I have a comment section. It is comprised of 3 major files. One file creates the form where you fill in your name and comment. Another file sends your comment to the DB. The third file displays the already existing comments on the page. You have the option to reply to the existing comments on the page. When you click the reply button I would like the comment text box to light up so the user knows its working but I have hit a brick wall. 

 

This is the comment form the user actually types into:

<div id="comment-container" > 
<form id="comment_form" action="/comm_1/post_comment.php" method='post' onsubmit=" return validateForm()">
		<table>	
		<tr>
			<td id="error"></td>
		</tr>
		<tr>
			<td><textarea name="comment_body" id='comment_body' placeholder="Comment"></textarea></td>
		</tr>
		<?php if(!$username && !$userid): ?>
		<tr>
			<td><input type="text" name="name" class="input_style" placeholder="Name"/>
			<input type="submit" id="loginbtn" value="Or Login" onclick="window.location='/login_scripts/login.php'" /></td>
		</tr>
		<tr>
			<td><input type="email" name="email" class="input_style" placeholder="Email"/></td>
		</tr>
		<?php endif; ?>
		<?php if($username && $userid): ?>
			<input type="hidden" name="name" value="<?php echo htmlspecialchars($username) ?>"/>
			<input type="hidden" name="email"  value="<?php echo htmlspecialchars($email) ?>"/>
		<?php endif; ?>
		<tr>
			<input type='hidden' name='parent_id' id='parent_id' value='0'/>
			<td><input type="submit" name="submitbtn" id="submitbtn" value="Add comment"/></td>
		</tr>
		</table>	
	</form>

This how the existing comments are displayed on the page: 

 

You can see on line 7 is the button to the reply to a comment. When this is clicked I need the "comment_body" from the above code to highlight.

<?php
function getComments($row) {
	echo "<li class='comment'>";
	echo "<div class='aut'>".$row['author']."</div>";
	echo "<div class='timestamp'>".$row['created_at']."</div>";
	echo "<div class='comment-body'>".$row['comment']."</div>";
	echo "<a href='#comment_form' name='replybtn' class='reply' id='".$row['id']."'>Reply</a></script>";
	$q = "SELECT * FROM threaded_comments WHERE parent_id = ".$row['id']."";
	$r = mysql_query($q);
	echo "</li>";
	if(mysql_num_rows($r)>0)
		{
		echo "<ul>";
		while($row = mysql_fetch_assoc($r)) {
			getComments($row);
		}
		echo "</ul>";
		}	
}
?>

I tried this with JS, but it does not work: 

$(function(){
	$("a.reply").click(function() {
		var id = $(this).attr("id");
		$("#parent_id").attr("value", id);
		$("#comment_body").focus();    
	});
});

Edited January 27, 2015 by ryanmetzler3