node.js解决跨域问题

var app = express();//设置跨域访问app.all('*', function(req, res, next) {    res.header("Access-Control-Allow-Origin", "*");    res.header("Access-Control-Allow-Headers", "X-Requested-With");    res.header("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");    res.header("X-Powered-By",' 3.2.1')    res.header("Content-Type", "application/json;charset=utf-8");    next();});