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Node.js Development in 2020: trends and techniques by Nikita Galkin Nov 8, 2019

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What anniversary is today?

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Why Node.js won the market? 1. Everybody knows JavaScript 2. Everybody loves Open Source 3. Google pay for V8 4. Performance boost every release 5. There is a release schedule

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nvm install 12.13.0 nvm alias default 12.13.0 nvm reinstall-packages 10.16.3 Migrate your local version easy with nvm:

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Node.js v12 Breaking changes

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Breaking change at Event Loop for Timers and Microtasks

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setTimeout(() => console.log('timeout1')); setTimeout(() => { console.log('timeout2'); Promise.resolve().then(() => console.log('promise resolve') ); }); setTimeout(() => console.log('timeout3')); setTimeout(() => console.log('timeout4'));

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6.8 ➜ 7.7

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➜ ~ nvm use v10 Now using node v10.16.3 (npm v6.9.0) ➜ ~ node --print process.versions.v8 6.8.275.32-node.54 ➜ ~ nvm use v12 Now using node v12.13.0 (npm v6.12.0) ➜ ~ node --print process.versions.v8 7.7.299.13-node.12 6.8 ➜ 7.7

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const array = []; for (let i = 1; i < 10000; i++) array.push(i); console.time('assign'); const assign = array.reduce( (acc, curr) => Object.assign(acc, {[curr]: curr}), {}); console.timeEnd('assign'); console.time('spread'); const spread = array.reduce( (acc, curr) => ({...acc, [curr]: curr}), {}); console.timeEnd('spread');

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1. Faster JavaScript parsing 2. Faster async functions and promises 3. Zero-cost async stack traces

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const { promisify } = require('util'); const wait = promisify(setTimeout); async function testAsyncStacktrace() { await wait(10); await willDie(); return 42; } async function willDie() { await Promise.resolve(); throw new Error('#Feelsbadman'); } testAsyncStacktrace() .catch(error => console.log(error.stack));

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By default stack-trace is 10 On CLI level ➜ ~ node async-stack-trace.js \ --stack-trace-limit=1000 On code level Error.stackTraceLimit = Infinity; More

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Node.js features

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Node.js v12 disappointments 1. ECMAScript Modules support is not stable. Again. 2. Most native modules are callback based. Only fs and dns modules have promises.

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JavaScript designed for browser where a failure affects only one tab, only one user. But at Node.js failing affect everything...

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Worker Threads are no longer experimental!

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New http parser llhttp based on llparse

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1. You use it! 2. For your own parser 3. TypeScript Why learn how it works?

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native Promises

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1. Faster JavaScript parsing 2. Faster async functions and promises 3. Zero-cost async stack traces

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What need to know: 1. promisify from util 2. once from events 3. Reading streams asynchronously

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function wait(timeout) { return new Promise(resolve => { setTimeout(resolve, timeout)); }); } // VS const util = require('util'); const wait = util.promisify(setTimeout);

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const { EventEmitter } = require('events'); const emitter = new EventEmitter(); async function getPromise() { return new Promise(resolve => { emitter.once('eventName', resolve); }) }

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const { EventEmitter } = require('events'); const { once } = require('events'); const emitter = new EventEmitter(); async function getPromise() { return once( emitter, 'eventName'); }

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const { EventEmitter } = require('events'); const emitter = new EventEmitter(); async function getPromise() { return new Promise(resolve => { emitter.once('eventName', resolve); }) }

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async function main(filePath) { const readStream = fs.createReadStream(filePath); for await (const chunk of readStream) { console.log('>>> '+chunk); } console.log('### DONE ###'); }

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What need to use: 1. Promise.all/Promise.race 2. p-limit 3. multipleResolves from process

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Next big thing is QUIC/HTTP3

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Node.js news

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1. Node.js Foundation and JS Foundation Merge to Form OpenJS Foundation 2. Node.js certification 3. Nodejs.dev arrived

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1. Boolean 2. Null 3. Undefined 4. Number 5. String 6. Symbol 7. Object Data types in JavaScript.

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1. Boolean 2. Null 3. Undefined 4. Number 5. String 6. Symbol 7. Object 8. BigInt Data types in JavaScript.

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Not only Node.js news

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1. TC39 new proposals 2. GraphQL is not hype and has foundation. 3. Nestjs is the most promising framework

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TypeScript 3.7

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HAPPY NODE.JS DEVELOPMENT! You can find me on Twitter as @galk_in Slides are available at speakerdeck.com/galkin or at my site galk.in