如何在axios中提交token，为何总报错

Question

浏览器报错：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:8081' is therefore not allowed access. The response had HTTP status code 403.

代码：

   this.$axios({
        method: "get",
        url: "http://192.168.3.10:8080/MayaCloud_Login/getPermissionTree",
        headers:{
          sessionUser :sessionStorage.getItem("token")
        },
      })

Answer 1

是因为你为你的请求头部添加了一个sesstionUser，并不在简单请求的范围内，所以浏览器会发送一个预检请求
详细简单请求和复杂请求区别看这里
https://developer.mozilla.org...

解决办法很简单，后台为你设置的头添加跨域允许就可以了，要在对预检请求的处理里添加

("Access-Control-Allow-Headers", "sessionUser");

Answer 2

报错随便一搜也知道是跨域了吧。