@jsenv/server

server

@jsenv/server helps to write flexible server code with a declarative API.

import { startServer } from "@jsenv/server"

await startServer({
  protocol: "http",
  port: 8080,
  requestToResponse: () => {
    return {
      status: 200,
      headers: {
        "content-type": "text/plain",
      },
      body: "Hello world",
    }
  },
})

Example

Code starting a server and using node-fetch to send a request on that server:

import fetch from "node-fetch"
import { startServer } from "@jsenv/server"

const server = await startServer({
  requestToResponse: () => {
    return {
      status: 200,
      headers: {
        "content-type": "text/plain",
      },
      body: "Hello world",
    }
  },
})

const response = await fetch(server.origin)
const responseBodyAsText = await response.text()
console.log(responseBodyAsText) // "Hello world"

Code starting a server with 2 request handlers:

/*
 * starts a server which:
 * - when requested at "/"
 *   -> respond with 200
 * - otherwise
 *   -> respond with 404
 */
import { startServer, composeServices } from "@jsenv/server"

const indexService = (request) => {
  if (request.ressource === "/") {
    return { status: 200 }
  }
  return null // means "I don't handle that request"
}

const notFoundService = (request) => {
  return { status: 404 }
}

const server = await startServer({
  requestToResponse: composeServices({
    index: indexService,
    otherwise: notFoundService,
  }),
})

const fetch = await import("node-fetch")
const responseForOrigin = await fetch(server.origin)
responseForOrigin.status // 200

const responseForFoo = await fetch(`${server.origin}/foo`)
responseForFoo.status // 404

Code starting a server in https:

import { readFileSync } from "node:fs"
import { startServer } from "@jsenv/server"

await startServer({
  protocol: "https",
  certificate: readFileSyncAsString("./server.crt"),
  privateKey: readFileSyncAsString("./server.key"),
  allowHttpRequestOnHttps: true,
  requestToResponse: (request) => {
    const clientUsesHttp = request.origin.startsWith("http:")

    return {
      status: 200,
      headers: {
        "content-type": "text/plain",
      },
      body: clientUsesHttp ? `Welcome http user` : `Welcome https user`,
    }
  },
})

function readFileSyncAsString(relativeUrl) {
  const fileUrl = new URL(relativeUrl, import.meta.url)
  return String(readFileSync(fileUrl))
}

Code starting a server for static files:

import { startServer, fetchFileSystem } from "@jsenv/server"

await startServer({
  requestToResponse: async (request) => {
    const fileUrl = new URL(request.ressource.slice(1), import.meta.url)
    const response = await fetchFileSystem(fileUrl, {
      ...request,
    })
    return response
  },
})

Documentation

• https
• Serving files
• Handling requests
• Handling errors
• Server timing
• CORS
• Content negotiation
• Server Sent Events
• Cluster
• Http2 push

Installation

npm install @jsenv/server