Simple for-await JSON body parser for Koa (node.js)

bodyparser.js

const { StringDecoder } = require('string_decoder')
const decoder = new StringDecoder() // default utf8

// Note that this is a naive example
// There's no safe-guarding and the process could be flooded easily b/c there's no limits.
// This is just to illustrate how to use for-await in Koa
async function bodyParser (ctx, next) {
  let acc = ''
  for await (const chunk of ctx.req) acc += decode.write(chunk)
  ctx.state.body = JSON.parse(acc)
  await next()
}

example_koa.js

// Example usage, simple Koa application
const Koa = require('koa')
const app = new Koa()

app.use(bodyParser)

app.use(async (ctx) => {
  ctx.body = ctx.state.body
})

app.listen(8000)

example_koa_router.js

// Example usage, simple Koa application
const Koa = require('koa')
const Router = require('@koa/router')
const app = new Koa()
const r = new Router()

r.post('/', bodyParser, async (ctx) => {
  ctx.body = ctx.state.body
})

app
  .use(r.routes())
  .use(r.allowedMethods())
  .listen(8000)