http-ndjson

3.1.0 verified Sat May 09 auth: no javascript

Log HTTP requests and responses as ndjson (newline-delimited JSON). Version 3.1.0 is the latest stable release. It is designed to work well with bole and garnish for pretty-printing. Minimal dependencies and a focus on standard request/response properties. Use it to produce structured logs that can be piped to other ndjson-consuming tools.

Common errors

error TypeError: httpNdjson is not a function ↓

cause Using destructured import like `const { httpNdjson } = require('http-ndjson')`, which yields undefined.

fix

Use const httpNdjson = require('http-ndjson') without destructuring.

error ERR_REQUIRE_ESM: require() of ES Module not supported ↓

cause Attempting to require() the package in an ESM-only project, but the package is CJS. This error occurs when the project's package.json has "type": "module".

fix

Use dynamic import(): import('http-ndjson').then(m => m.default), or change the project to CommonJS.

error TypeError: setSize is not a function ↓

cause Calling httpNdjson without providing a callback, or passing a non-function as the last argument.

fix

Ensure you pass a callback function as the third argument: const setSize = httpNdjson(req, res, console.log)

Warnings

breaking Version 3.0.0 changed the API: the callback signature now receives the message object; previously it received separate arguments. ↓

fix Update your callback to accept the ndjson object directly (e.g., `console.log(msg)` instead of `console.log(msg1, msg2)`).

gotcha The function returns a `setSize` function that must be called with the response body length. Calling it with the wrong value may cause incorrect logging of response size. ↓

fix Always pass the correct byte length of the response body to the returned function (e.g., `setSize(Buffer.byteLength(body))`).

gotcha The package does not support ES modules (ESM). Attempting to import it with `import` will throw an error in Node.js if the project is configured as ESM. ↓

fix Use `require()` or configure your project to use CommonJS. Alternatively, use a dynamic import with a bundler that can handle CJS.

deprecated The `opts` parameter can be a function for custom fields, but this is not deprecated yet. No specific deprecations noted. ↓

fix No action needed.

Install

npm install http-ndjson

yarn add http-ndjson

pnpm add http-ndjson

Imports

default
wrong
```
import httpNdjson from 'http-ndjson'
```
correct
```
const httpNdjson = require('http-ndjson')
```
This package is CJS-only; ES module imports will fail unless using a bundler that can handle them.

default

wrong

const log = require('http-ndjson').httpNdjson

correct

const httpNdjson = require('http-ndjson')

The package exports a single function; there is no named export.

default

wrong

const { httpNdjson } = require('http-ndjson')

correct

const httpNdjson = require('http-ndjson')

Destructuring will result in undefined; the function is the default export.

Quickstart

Shows how to create an HTTP server and log requests/responses as ndjson using the default callback (console.log).

const httpNdjson = require('http-ndjson')
const http = require('http')

http.createServer((req, res) => {
  const log = console.log
  const setSize = httpNdjson(req, res, log)
  const body = 'OK'
  setSize(body.length)
  res.end(body)
}).listen(3000, () => console.log('Server listening on 3000'))