node.js 报错 Cannot read property 'username' of undefined

Question

点击登录就提示这个错误，但找不到原因

 TypeError: **Cannot read property 'username' of undefined**

login.js

前台js:获取输入的username password 拼成一个数组传给后台，

Answer 1

First: You should make sure ajax method is same as routers' method
Second: You should make sure parse the data in body.

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
  extended: true
}));

Answer 2

contentType: "application/json;charset=utf-8"

Answer 3

bodyThe data cannot be obtained.
It may be that header is application/x-www-form-urlencoded, and datatype is caused by JSON.

If you want to obtain JSON data in the background, you need to ensure that the middleware of express is used

app.use(bodyParser.json());

Answer 4

How did the original poster solve it? I encountered the same problem

TypeError: Cannot read property 'name' of undefined