What does the extended property in the urlencoded method in body-parser do?

Question

Express.js

I programmed a small server:

const express = require('express')
const bodyParser = require('body-parser')
const app = express()

const urlencodedParser = bodyParser.urlencoded({extended: true});

app.get('/message', (request, response) => {
  response.sendFile(__dirname + '/message.html')
})

app.post('/message', urlencodedParser, (request, response) => {
  if (!request.body) return response.sendStatus(400)
  console.log(request.body.name + " написал: " + request.body.message)
  response.redirect("/message")
})

app.listen(3000, () => {
  console.log('Сервер запущен на порте: 3000')
})

I don’t understand why the extended property is needed, I set true and false, everything works the same, maybe it adds additional properties when true? If so, which ones?

Answer 1

How about reading the doc first?