Conditional Statement if no value exists in PHP or Jquery

I created an unordered list with the following html:

<ul id="infoBox">
         <li class="facebook"><a href="<?php echo get_field('facebook_page'); ?>"><?php the_title(); ?> on Facebook</a></li>
         <li class="twitter"><a href="<?php echo get_field('twitter_page'); ?>">Follow <?php the_title(); ?> on Twitter</a></li>
         <li class="youtube"><a href="<?php echo get_field('youtube_开发者_Python百科page'); ?>">Watch <?php the_title(); ?> on Youtube</a></li>
 </ul>

<?php echo get_field('value'); ?> is grabbing a string from the backend of my site. Sometimes, I do not have a string to display, so I want to create a conditional statement in jquery and/or php that basically says: If there is no field to get (if the field is left empty on the backend), do not display the list item at all. For instance, if a band doesn't have a youtube page, do not display the list item with a class of 'youtube' at all.

Any idea how I would go about this?

<ul id="infoBox">
    <?php $response = get_field('facebook_page'); 
    if(!empty($response)): ?><li class="facebook"><a href="<?php echo $response; ?>"><?php the_title(); ?> on Facebook</a></li><?php endif; ?>
    <?php $response = get_field('twitter_page');
    if(!empty($response)): ?><li class="twitter"><a href="<?php echo $response; ?>">Follow <?php the_title(); ?> on Twitter</a></li><?php endif; ?>
    <?php $response = get_field('youtube_page');
    if(!empty($response)): ?><li class="youtube"><a href="<?php echo $response; ?>">Watch <?php the_title(); ?> on Youtube</a></li><?php endif; ?>
</ul>

Would this work for you?

if(get_field('value') == '' || is_null(get_field('value')) 
   echo 'no value';
else
   echo 'there is a value';

I hope understand your question and could help.

<ul id='infoBox'>
<?php
    $name = the_title();
    $potentialItems = array('facebook' => "$name on facebook", 
                            'youtube' => "Watch $name on youtube", 
                            'twitter' =? "Follow $name on twitter");

   foreach($potentialItems as $k=>$v)
   {
        $gf = get_field($k.'_page');
        if($gf)
        {
            echo "<li class='$k'><a href='$gf'>$v</a></li>";
        }
   }
?>
</ul>