for (var i = 0; i < 3; i++) {
script[i].src =www.miweb.com/feeds/posts/default/-/"+cat[i]+"?max-results=3&orderby=published&alt=json-in-script&callback=showCat";
}

www.miweb.com/feeds/posts/default/-/"+cat1+"?max-results=3&orderby=published&alt=json-in-script&callback=showCat";

www.miweb.com/feeds/posts/default/-/"+cat2+"?max-results=3&orderby=published&alt=json-in-script&callback=showCat";

www.miweb.com/feeds/posts/default/-/"+cat3+"?max-results=3&orderby=published&alt=json-in-script&callback=showCat";

www.miweb.com/feeds/posts/default/-/"+cat2+"?max-results=3&orderby=published&alt=json-in-script&callback=showCat";

www.miweb.com/feeds/posts/default/-/"+cat1+"?max-results=3&orderby=published&alt=json-in-script&callback=showCat";

www.miweb.com/feeds/posts/default/-/"+cat3+"?max-results=3&orderby=published&alt=json-in-script&callback=showCat";