Getting category slug from posts in the loop

Hello! I am trying to figure out a way to output the category slugs for each of the posts in the loop.

My general loop looks like this:

<?php
// The Query
$the_query = new WP_Query($args);

// The Loop
while ( $the_query->have_posts() ) : $the_query->the_post();?>

and I am trying to put each post in between <li>. I want to give each post a class within the <li> tag that consists of their category slugs (this is for JQuery purposes).
I found this in a tutorial, but it doesn’t work for me:

<li class="<?php foreach((get_the_category()) as $category) {
echo get_cat_slug($category->cat_ID) . ' ';} ?> ">

I think I have to modify something like this, but I’m not sure. help?

<?php
$category = get_the_category();
$cat_=name =  $category[0]->cat_name;
?>