How I can verify that an incomming http body is multipart/form-data using regex and nodejs?

At my nodejs project, I want to validate if an incoming http request is just a valid multipart/form-data one.

So far I tried the following example:

const http = require('http')
const validateMultipartFormData = (body) => {
   // Somehow use a logic to verify whether body is a multipart one.
   //