axios、node交互跨域请求

axios不能跨域请求，但是如何服务器端设置了
res.header(“Access-Control-Allow-Origin”, ‘*’);访问权限所有
axios便能够访问了

在此中如何未设置access-control-allow-origin,post请求报错
Failed to load http://localhost:3000/goods/addCart: Response to preflight request doesn’t pass access control check: No ‘Access-Control-Allow-Origin’ header is present on the requested resource. Origin ‘http://localhost:8080’ is therefore not allowed access.

在此中如何未设置access-control-allow-origin,get请求报错
Failed to load http://localhost:3000/goods/list?page=4&pageSize=8&sort=1&priceLevel=all: No ‘Access-Control-Allow-Origin’ header is present on the requested resource. Origin ‘http://localhost:8080’ is therefore not allowed access.

为post请求设置access-control-allow-origin，又会报一个错
Request header field Content-Type is not allowed by Access-Control-Allow-Headers in preflight respon

最终实现的解决方案：
在app.js设置统一设置

//设置跨域访问app.use(function (req, res, next) {  res.header('Access-Control-Allow-Origin', '*');  res.header('Access-Control-Allow-Headers', 'Content-Type, Content-Length, Authorization, Accept, X-Requested-With , yourHeaderFeild');  res.header('Access-Control-Allow-Methods', 'PUT, POST, GET, DELETE, OPTIONS');  if (req.method == 'OPTIONS') {    res.send(200); /*让options请求快速返回*/  } else {    next();  }})