• This is a small piece of Javascript code to add a caption to a table.
• Works with DokuWiki's default template.
• Works with WRAP plugin.
• Just add a line of <WRAP caption>Caption text</WRAP> before the table.

Add the following code to your conf/userscript.js.

add_caption.js

jQuery('.page div.table>table').each(function (index) {
  let $table = jQuery(this);
  let $prevDiv = $table.parent().prev();
  if ($prevDiv.hasClass('wrap_caption') || $prevDiv.hasClass('caption')) {
    if ($prevDiv.children('p').length > 0) {
      let captionText = $prevDiv.children('p').html();
      $table.prepend('<caption>' + captionText + '</caption>');
      $prevDiv.remove();
      if (location.hash) {
        location.href = location.hash;
      }
    }
  }
});

Probably you like to add the following lines or similar to your conf/userall.css.

styles.css

caption {
  text-align: center;
  font-weight: bold;
}

The default syntax of a table is like this:

^ No. ^ Description ^ Quantity ^ Remark ^
| 1   | Lorem ipsum dolor sit amet | 100 |Euismod posuere mus lobortis |
| 2   | Konsectetur adipiscing elit molestie  | 50 |Aenean sed ornare|
| 3   | Scelerisque vestibulum metus risus |25 |Sociis mollis, morbi proin suspendisse magnis|
| 4   | Nunc a commodo nullam | 200 |  |

The above code is rendered as follows:

Add one line above the table like this:

<WRAP caption>Table 2. Caption text is displayed like this</WRAP>

^ No. ^ Description ^ Quantity ^ Remark ^
| 1   | Lorem ipsum dolor sit amet | 100 |Euismod posuere mus lobortis |
| 2   | Konsectetur adipiscing elit molestie  | 50 |Aenean sed ornare|
| 3   | Scelerisque vestibulum metus risus |25 |Sociis mollis, morbi proin suspendisse magnis|
| 4   | Nunc a commodo nullam | 200 |  |

this is rendered as:

Since the caption is inserted within the table, it aligns with the table, as shown below with a small table.

The original HTML text is:

<div class="wrap_caption">
  <p> Caption text</p>
</div>
<div class="table">
  <table>
     ...
  </table>
</div>

This is transformed to:

<div class="table">
  <table>
    <caption>Caption text</caption>
    ...
  </table>
</div>

Since this transformation is made after the rendering by DokuWiki, the normal formatting syntax (such as //italic//, __underline__, etc.) can be used in the caption text.