fetch - Missing boundary in multipart/form-data POST

Question

thanks for stopping by.

I want to send a new FormData() as the body of a POST request using the fetch api

the operatio

Answer 1

fetch(url,options)

1. If you set a string as options.body, you have to set the Content-Type in request header ,or it will be text/plain by default.

2. If options.body is specific object like let a = new FormData() or let b = new URLSearchParams(), you don't have to set the Content-Type by hand.It will be added automaticlly.

   • for a ,it will be something like

   multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW

   as you see, the boundary is automaticlly added.

   • for b, it is application/x-www-form-urlencoded;