Whats New in Node 10

JaxNode November 2018

There is no Roadmap for Node!

Node versions

  • Node LTS version 10
  • Node 11
  • openssl 1.1.0i
  • v8 v6.8.275.24
  • Node 11 v8 now at v7.0

Engines

  • V8 (Google)
  • ChakraCore (Microsoft)
  • JSCore (Apple)

New features

  • Async Hooks
  • Promise based modules
  • N-API
  • http/2
  • Time Travel Debugging
  • ESM (Ecmascript modules)
  • Worker Threads

2 Versions of Node?

  • 10 is the LTS version
  • Long Term Support
  • Ready for Production
  • 11 is experimental release

Async Hooks

  • Create callbacks that execute around system events
  • Used to provide additional info around system and can execute other behavior
  • Once created can be disabled or enabled
  • Experimental
class MyAsyncCallbacks {
  init(asyncId, type, triggerAsyncId, resource) { }
  destroy(asyncId) {}
}

class MyAddedCallbacks extends MyAsyncCallbacks {
  before(asyncId) { }
  after(asyncId) { }
}

const asyncHook = async_hooks.createHook(new MyAddedCallbacks());

Promise based Modules

  • Promise based versions of core Node APIs
  • File System
  • DNS
  • Domains
  • const fsPromises = require('fs').promises;
const fsPromises = require('fs').promises;

async function openAndClose() {
  let filehandle;
  try {
    filehandle = await fsPromises.open('thefile.txt', 'r');
  } finally {
    if (filehandle !== undefined)
      await filehandle.close();
  }
}

Addons N-API

  • Native C/C++ api for using native code
  • Abstraction layer
  • Will work with different engines 
  • V8, ChakraCore, JSCore
  • Most methods are experimental

http/2

  • http v1.1 very verbose
  • http v1.1 is request/response based
  • http/2 allows multiplexing
  • Can serve multiple files over same connection
  • Stable

http/2 gocthas

  • http/2 does not require TLS, but browsers do
  • Very easy to add certificates to http/2 server
  • Express requires plugin module to run http/2
  • Hapi supports http/2
const http2 = require('http2');
const fs = require('fs');

const server = http2.createSecureServer({
  key: fs.readFileSync('localhost-privkey.pem'),
  cert: fs.readFileSync('localhost-cert.pem')
});
server.on('error', (err) => console.error(err));

server.on('stream', (stream, headers) => {
  // stream is a Duplex
  stream.respond({
    'content-type': 'text/html',
    ':status': 200
  });
  stream.end('<h1>Hello World</h1>');
});

server.listen(8443);
// Generate certs for example
openssl req -x509 -newkey rsa:2048 -nodes -sha256 -subj '/CN=localhost' \
  -keyout localhost-privkey.pem -out localhost-cert.pem

Time Travel Debugging

  • Can go forwards and backwards with debugging
  • Available in ChakraCore
  • Used in conjunction with VSCode

ESM Modules

  • Allows for use of `import` and `export` keywords
  • Part of the ES6/2015 spec
  • React has been using this for years
  • ESM modules use *.mjs extension
  • Node currently differentiates between CJS/MJS
  • No one is happy with ESM modules

Demo

New Language Features

  • ES2015/16/17
  • Most features added in Node 4 and 6
  • Async/Await came in Node v8

ES2015 Features in Node 4

Let and Const

Iterators and Generators

Arrow => functions

Reflection

New literals

Template Strings

Classes

Lexical Scoping

Maps, Set, WeakMap

ArrayBuffer

Promises

Octal support

Node 6 features

  • ...Spread Operator
  • New Buffer
  • Default Parameters
  • Destructuring

Resources

  • https://medium.com/@atulanand94/beginners-guide-to-writing-nodejs-addons-using-c-and-n-api-node-addon-api-9b3b718a9a7f
  • https://hackernoon.com/node-js-tc-39-and-modules-a1118aecf95e
  • https://medium.com/webpack/the-state-of-javascript-modules-4636d1774358

Questions?

Whats New in Node 10

By David Fekke

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Whats New in Node 10

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