dx-server - modern, unopinionated, and satisfactory server

Install

yarn add dx-server jchain

Usage

Check below sample with comment for more details.

Simple server

import {Server} from 'node:http'
import chain from 'jchain'
import dxServer, {getReq, getRes, router, setHtml, setText,} from 'dx-server'

new Server().on('request', (req, res) => chain(
		dxServer(req, res),
		async next => {
			try {
				getRes().setHeader('Cache-Control', 'no-cache')
				console.log(getReq().method, getReq().url)
				await next()
			} catch (e) {
				console.error(e)
				setHtml('internal server error', {status: 500})
			}
		},
		router.get({
			'/'() {setHtml('hello world')},
			'/health'() {setText('ok')}
		}),
		() => setHtml('not found', {status: 404}),
	)()
).listen(3000, () => console.log('server is listening at 3000'))

File server:

import {Server} from 'node:http'
import chain from 'jchain'
import dxServer, {chainStatic, getReq, getRes, setHtml} from 'dx-server'
import {resolve, dirname} from 'node:path'
import {fileURLToPath} from 'node:url'

new Server().on('request', (req, res) => chain(
		dxServer(req, res),
		async next => {
			try {
				getRes().setHeader('Cache-Control', 'no-cache')
				console.log(getReq().method, getReq().url)
				await next()
			} catch (e) {
				console.error(e)
				setHtml('internal server error', {status: 500})
			}
		},
		chainStatic('/', {root: resolve(dirname(fileURLToPath(import.meta.url)), 'public')}),
		() => setHtml('not found', {status: 404}),
	)()
).listen(3000, () => console.log('server is listening at 3000'))

More complex server with express. This sample additionally requires: yarn install express morgan

import {Server} from 'node:http'
import {promisify} from 'node:util'
import chain from 'jchain'
import dxServer, {
	getReq, getRes,
	getBuffer, getJson, getRaw, getText, getUrlEncoded, getQuery,
	setHtml, setJson, setText, setBuffer, setRedirect, setNodeStream, setWebStream, setFile,
	router, connectMiddlewares, chainStatic, makeDxContext
} from 'dx-server'
import {expressApp} from 'dx-server/express'
import express from 'express'
import morgan from 'morgan'

// it is best practice to create custom error class for non-system error
class ServerError extends Error {
	name = 'ServerError'

	constructor(message, status = 400, code = 'unknown') {
		super(message)
		this.status = status
		this.code = code
	}
}

const authContext = makeDxContext(async () => {
	if (getReq().headers.authorization) return {id: 1, name: 'joe (private)'}
})

const requireAuth = () => {
	if (!authContext.value) throw new ServerError('unauthorized', 401, 'unauthorized')
}

const serverChain = chain(
	next => {
		// this is the difference between express and dx-server
		// req, res can be accessed from anywhere via context which uses NodeJS's AsyncLocalStorage under the hood
		getRes().setHeader('Cache-Control', 'no-cache')
		return next() // must return or await
	},
	async next => {// global error catching for all following middlewares
		try {
			await next()
		} catch (e) {// only app error message should be shown to user
			if (e instanceof ServerError) setHtml(`${e.message} (code: ${e.code})`, {status: e.status})
			else {// report system error
				console.error(e)
				setHtml('internal server error (code: internal)', {status: 500})
			}
		}
	},
	connectMiddlewares(
		morgan('common'),
		// cors(),
	),
	await expressApp(app => {// any express feature can be used. This requires express installed, with for e.g., `yarn add express`
		app.set('trust proxy', true)
		if (process.env.NODE_ENV !== 'production') app.set('json spaces', 2)
		app.use('/public', express.static('public'))
	}),
	authContext.chain(), // chain context will set the context value to authContext.value in every request
	router.post({// example of catching error for all /api/* routes
		async '/api'({next}) {
			try {
				await next()
			} catch (e) {
				if (e instanceof ServerError) setJson({// only app error message should be shown to user
					error: e.message,
					code: e.code,
				}, {status: e.status})
				else {// report system error
					console.error(e)
					setJson({
						message: 'internal server error',
						code: 'internal'
					}, {status: 500})
				}
			}
		}
	}, {end: false}), // note: {end: false} is required to match all /api/* routes. This option is passed directly to path-to-regexp
	router.post({
		'/api/sample-public-api'() { // sample POST router
			setJson({name: 'joe'})
		},
		'/api/me'() { // sample private router
			requireAuth()
			setJson({name: authContext.value.name})
		},
	}),
	router.get({ // sample GET router
		'/'() {
			setHtml('ok')
		},
		'/health'() {
			setHtml('ok')
		}
	}),
	() => { // not found router
		throw new ServerError('not found', 404, 'not_found')
	},
)

const tcpServer = new Server()
	.on('request', async (req, res) => {
		try {
			await chain(
				dxServer(req, res, {jsonBeautify: process.env.NODE_ENV !== 'production'}), // basic dx-server context
				serverChain,
			)()
		} catch (e) {
			console.error(e)
			res.end()
		}
	})

await promisify(tcpServer.listen.bind(tcpServer))(3000)
console.log('server is listening at 3000')

Note:

getBuffer, getJson, getRaw, getText, getUrlEncoded, getQuery are all synchronous functions. The associated results are calculated in the first time they are called and cached for subsequent calls.

If you want to get these values synchronously, chain it, like follows:

import {getJson} from 'dx-server'

chain(
	getJson.chain(/*option*/), // json body is parsed and stored in context in every request
	next => {
		console.log(getJson.value) // json body can be accessed synchronously
		return next()
	}
)

Context can be created using makeDxContext function:

import {makeDxContext} from 'dx-server'

const authContext = makeDxContext(() => {
	if (getReq().headers.authorization) return {id: 1, name: 'joe (authorized)'}
})
const requireAuth = () => {
	if (!authContext.value) throw new Error('unauthorized')
}
chain(
	authContext.chain(),
	next => {
		requireAuth()
		return next()
	}
)
// or await authContext() to lazy load the context and don't require chaining authContext.chain()
chain(
	async next => {
		console.log(await authContext())
		return next()
	}
)

API References

All exported APIs:

import dxServer, {
	getReq, getRes, getBuffer, getJson, getRaw, getText, getUrlEncoded, getQuery,
	setHtml, setJson, setText, setBuffer, setRedirect, setNodeStream, setWebStream, setFile,
	router, connectMiddlewares, chainStatic, makeDxContext
} from 'dx-server'
import {expressApp, expressRouter} from 'dx-server/express' // requires express installed
import {
	setBufferBodyDefaultOptions,
	bufferFromReq, jsonFromReq, rawFromReq, textFromReq, urlEncodedFromReq, queryFromReq,
} from 'dx-server/helpers'

• getReq(), getRes(): get request and response objects from anywhere.

• getBuffer(), getJson(), getRaw(), getText(), getUrlEncoded(), getQuery(): get parsed request body, raw body, text body, url encoded body, query string from anywhere. These are DX context object, can be used as follows:

  • const json = await getJson(): lazily load the context, once loaded, it is cached for subsequent calls.
  • Chain it to get the value synchronously: chain(getJson.chain(), next => console.log(getJson.value)). Note that the value is calculated in every request.

• makeDxContext(fn): create a DX context object.

• setHtml, setJson, setText, setBuffer, setRedirect, setNodeStream, setWebStream, setFile: set response body.

• router.get, router.post, router.put, router.delete, router.patch, router.head, router.options, router.connect, router.trace: create router.

• router.method(methods, routes, options): create router with custom methods.

• router.all(routes, options): create router for all methods.

• connectMiddlewares(...middlewares): connect middlewares. For example:

import {connectMiddlewares} from 'dx-server'
import morgan from 'morgan'
import cors from 'cors'

connectMiddlewares(
	morgan('common'),
	cors(),
)

• chainStatic(path, options): serve static files. For example:

import {chainStatic} from 'dx-server'
import {resolve, dirname} from 'node:path'
import {fileURLToPath} from 'node:url'

chain(
	chainStatic('/assets', {root: resolve(dirname(fileURLToPath(import.meta.url)), 'public')})
)