post 坑

express post 后存到后端需要解析
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: false}));

https://www.npmjs.com/package/multer#readme
bodyParser
This does not handle multipart bodies, due to their complex and typically large nature. For multipart bodies, you may be interested in the following modules:

• busboy and connect-busboy
• multiparty and connect-multiparty
• formidable
• multer

This module provides the following parsers:

• JSON body parser
• Raw body parser
• Text body parser
• URL-encoded form body parser