crawl two url using for loop , poor

loopCrawler.js

    function download(url, callback){
        http.get(url, function(res){
                var data="";

                res.on('data', function(chunk){
                    data += chunk;
                    });

                res.on('end', function(){
                    callback(data);
                    });

                }).on('error', function(){
                    callback(null);
                    });
    }

    var urls=["http://renren.com", "http://www.sina.com.cn"];

    for(var i=0; i<urls.length; i++){
        download(urls[i],function(data){
                var urlPattern = /^(https?:\/\/)([\da-z\.-]+).\.([a-z\.]{2,10})([\/\w\.-]*)*\/?$/;

                var $ = cheerio.load(data);

                console.log("----url----"+i);

                $("a").each(function(i, e){
                    var url = $(e).attr("href");

                    if(urlPattern.exec(url))
                    console.log(url);
                });
        });
    }