node+express框架解决跨域自己学习前端的过程中，用express搭的后台，解决跨域问题。直接把下面这段代码复制

直接把下面这段代码复制到app.js文件所有路由的最前方就可以了

  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();
});