Get featured image and additional posts thumbnail WordPress REST API

(function($){
  $(document).ready(function(){
    var items = [];
    $.getJSON('https://localhost/wordpress/wp-json/wp/v2/posts?category_name=portfolio&per_page=50&_embed', function(response){
      console.log(response);
      $.each(response, function(key,val){
        //console.log(val._embedded['wp:featuredmedia'][0].source_url);
        items.push(''+''+
                     '');
      });
    });

  });
}(jQuery));

//use variable array to push data