Is there a better way to do this than echo?

Question

I'm working PHP guest book which has some form validation (such as field highlighting when there is an error) that I only know how to do with JavaScript.

I have a simple form that looks like this:

<form action="$_SERVER['SELF']" enctype="multipart/form-data" method="post">
    <label for="guest_name">Guest Name:</label>
    <input id="post-name" class="noerror" type="text" name="guest_name">
    <input type="submit" name="submit" value="Let 'er rip" />
</form>

Which I am validating with the following function:

//Name Validation
if(strlen($_POST["guest_name"]) != 0){
    global $Name;
    $Name = $_POST["guest_name"];
} else {
echo '<script type="text/javascript">
        $(document).ready(function(){
            $("#post-name").removeClass("noerror").addClass("error");
        });
     </script>';
}

It works but I can't help but feel like this is a terribly inefficient way to go about this but my knowledge of PHP isn't quite there yet to figure out how to optimize this.

Answer 1

Don't rely on js

You can do that kind of thing without js any number of ways for example:

<form action="" enctype="multipart/form-data" method="post">
    <label for="guest_name">Guest Name:</label>
    <?php
    $class = 'noerror';
    if(empty($_POST["guest_name"])){
        $class = '';
    }
    ?>
    <input id="post-name" class="<?php echo $class ?>" type="text" name="guest_name">
    <input type="submit" name="submit" value="Let 'er rip" />
</form>

Note that double-negatives can get easily confusing (there is not no error) as such it's a better idea to always use positive logic checks:

<?php
$class = '';
if(empty($_POST["guest_name"])){
    $class = 'error';
}
?>
<input id="post-name" class="<?php echo $class ?>" type="text" name="guest_name">

Sticking to that principle usually leads to simpler and easier to understand code.

Answer 2

This is also possible

<?php
    if(strlen($_POST["guest_name"]) != 0) :
        $Name = $_POST["guest_name"];
    else :
?>
    <script type="text/javascript">
        $(document).ready(function(){
            $("#post-name").removeClass("noerror").addClass("error");
        });
    </script>';
<?php endif; ?>

Answer 3

Don't send that huge script. Send a custom header with a simple error code. Your response handler can listen for headers (as distinct from the response text) and behave accordingly.