How to change a next/previous link to display post title in Wordpress?

Question

I am currently working on my wordpress site and have started to use a timeline. There are next/previous buttons in the post, but I want them to display the post title instead of Next/Previous. I have looked over the wordpress code for this, but the dev is using non-standard code to achieve it.

Could somebody take a look at the code and tell me what I need to change.

<div class="clearfix"></div>
            </div>
            <div class="timeline-info">
                <div class="timeline-content">
                    <?php 
                    $content =  preg_replace ('#<embed(.*?)>(.*)#is', ' ', get_the_content(),1);
                    $content =  preg_replace ('@<iframe[^>]*?>.*?</iframe>@siu', ' ', $content,1);
                    $content =  preg_replace ('/<source\s+(.+?)>/i', ' ', $content,1);
                    $content =  preg_replace ('/\<object(.*)\<\/object\>/is', ' ', $content,1);
                    $content =  preg_replace ('#\[video\s*.*?\]#s', ' ', $content,1);
                    $content =  preg_replace ('#\[audio\s*.*?\]#s', ' ', $content,1);
                    $content =  preg_replace ('#\[/audio]#s', ' ', $content,1);
                    preg_match_all('#\bhttps?://[^\s()<>]+(?:\([\w\d]+\)|([^[:punct:]\s]|/))#', $content, $match);
                    foreach ($match[0] as $amatch) {
                        if(strpos($amatch,'soundcloud.com') !== false){
                            $content = str_replace($amatch, '', $content);
                        }elseif(strpos($amatch,'youtube.com') !== false){
                            $content = str_replace($amatch, '', $content);
                        }
                    }
                    $content = preg_replace('%<object.+?</object>%is', '', $content,1);
                    echo apply_filters('the_content',$content);?>
                </div>
            </div>
            <?php 
            $we_sevent_navi = get_option('wpex_navi');
            if($we_sevent_navi!='no'){
                $wpex_navi_order = get_option('wpex_navi_order');
                $preevtrsl = get_option('wpex_text_prev')!='' ? get_option('wpex_text_prev') : esc_html__('Previous article','wp-timeline');
                $nextevtrsl = get_option('wpex_text_next')!='' ? get_option('wpex_text_next') : esc_html__('Next article','wp-timeline');
                if($wpex_navi_order!='ct_order'){ ?>
                    <div class="timeline-navigation defa">
                        <div class="next-timeline">
                            <?php next_post_link('%link', $nextevtrsl) ?>
                        </div>
                        <div class="previous-timeline">
                            <?php previous_post_link('%link', $preevtrsl) ?>
                        </div>
                    </div>
                    <?php 
                }else{
                    wpex_next_previous_timeline($preevtrsl,$nextevtrsl);
                }
            }?>
            <div class="clearfix"></div>
        </div>
  </div>

Answer 1

You can use WordPress default function to get next and previous post title with permalink something like this:

    <?php  // FOR PREVIOUS POST
        $prev_post = get_previous_post(); 
        $id = $prev_post->ID ;
        $permalink = get_permalink( $id );
    ?>
    <?php // FOR NEXT POST
        $next_post = get_next_post();
        $nid = $next_post->ID ;
        $permalink = get_permalink($nid);
    ?>

Then just use this variable in your HTML structure like below:

<div class="next-timeline">
     <?php next_post_link( '%link', __( 'Next <span class="meta-nav">&rarr;</span>', 'twentyeleven' ) ); ?>
     <h2><a href="<?php echo $permalink; ?>"><?php echo $next_post->post_title; ?></a></h2>
</div>
<div class="previous-timeline">
     <?php previous_post_link( '%link', __( '<span class="meta-nav">&larr;</span> Previous', 'twentyeleven' ) ); ?> 
     <h2><a href="<?php echo $permalink; ?>"><?php echo $prev_post->post_title; ?></a></h2>                           
</div>