Add multiple categories to body class Wordpress

SOLUTION

You can add this code to your custom functions.php file:

function add_categories( $classes = '' ) {

    $categories = get_the_category();
    foreach( $categories as $category ) {
    $classes[] = 'category-'.$category->slug;


}
 return $classes;
}
add_filter( 'body_class', 'add_categories' );

Fill Input Field with selected option with jquery

Here this you can use jquery on change function, check the example:

$("progadi").on("change", function() {

var val = $(this).val();
// put the val in other field

$("strata").val(val);
});