How to add a class to figure tag for featured images?

Question

I'd like to add a class to tag so that the caption for my featured image will show on hover.

Currently, this is the code when I use FireBug:

<div class="td-post-content">
<div class="td-post-featured-image">
<figure>
<a class="td-modal-image" data-caption="test caption lorem ipsum" href="http://nextwavecities.ph/wp-content/uploads/2015/06/11.jpg">
<figcaption class="wp-caption-text">test caption lorem ipsum</figcaption>
</figure>
</div>
</div>

I'd like to add: <figure class="wp-caption"> , but I don't have any idea which file should I edit. I am unable to find it on any of the PHP files in the theme.

When I upload an image to the blog post, the caption will show on-hover because the figure tag has the "wp-caption" class, except for the featured image.

Any one have an idea?

Answer 1

jQuery( document ).ready(function() {    
jQuery("figure").addClass("wp-caption");
});

You could use jQuery to add a class.