How to prohibit sending more than n number of requests from ip?

Question

Node.js

There is a code that subscribes users to mail chimp. So I don’t want one user to be able to conditionally make a million requests with mail using a script or somehow, how can I protect myself from this?

Here is the subscription code:

const express = require('express')
const bodyParser = require('body-parser')
const app = express()
const Mailchimp = require('mailchimp-api-v3')

app.use(bodyParser.json())
app.use(function (req, res, next) {
  res.setHeader('Access-Control-Allow-Origin', 'http://localhost:3000')
  res.setHeader('Access-Control-Allow-Methods', 'POST')
  res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type')
  res.setHeader('Access-Control-Allow-Credentials', true)
  next()
})

app.post('/subscribe',function (req, res) {
  const { email } = req.body
  const api_key = '...'
  const list_id = '...'
  const mailchimp = new Mailchimp(api_key)
  
  mailchimp.post(`lists/${list_id}`, {
    members: [{
      email_address: email,
      status: 'subscribed'
    }]
  })
    .then(result => res.send(result))
    .catch(error => res.send(error))
})

app.listen(1000)

Answer 1

Five seconds in google: https://www.npmjs.com/package/express-rate-limit
Keywords: rate limit, throttle.
Well, instead of manually setting CORS headers, there is also an npm module of the same name.