wordpress: previous_post_link() / next_post_link() placeholder

Answer 1

So you can "capture" what next_post_link() and previous_post_link() return using ob_start() and ob_get_clean(), then apply a conditional to it.

Code in practice:

$previous_string = "<-Back";
ob_start(); // start output buffering
previous_post_link("%link", $previous_string);
$previous_link = ob_get_clean(); // stop output buffering and store

if ($previous_link == '') {
  echo '<span style="color: #ccc">' . $previous_string . '</span>';
} else {
  echo $previous_link;
}

Answer 2

I never try this myself. However, you may refer to this post. It uses get_adjacent_post().