write figcaption into a data-title

HTML

<p>
<figure>
<a href="#" class="lightbox2" rel="lightbox[70]">
  <img src="http://placehold.it/350x150" width="350" height="150" alt="">
</a>
<figcaption>
caption one
</figcaption>
</figure>
	
</p>

<p>
<figure>
<a href="#" class="lightbox2" rel="lightbox[70]">
  <img src="http://placehold.it/350x150/cd11cd" width="340" height="140" alt="">
</a>
<figcaption>
caption two
</figcaption>
</figure>
	
</p>

<p>
<figure>
<a href="#" class="lightbox2" rel="lightbox[70]">
  <img src="http://placehold.it/350x150" width="350" height="150" alt="">
</a>
<figcaption>
caption thre
</figcaption>
</figure>
	
</p>

JavaScript

jQuery('figure').find('figcaption').each(function (index) {
        var desc = $(this).text();
        //var desc = jQuery('figcaption').text();
        console.log(index + desc);
        $(this).prev('.lightbox2').attr('data-title', ''+ desc +'');
        
    });