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Новое в JavaScript: ES.Next, ECMAScript 2020, ES11, ES10, ES9, ES8, ES7, ES6, ES2020, ES2019

Timur Shemsedinov, profile picture
Timur Shemsedinov

This document summarizes new features in JavaScript including ES2020 and beyond. It discusses updates to built-in objects like Array, Object, String, operators like optional chaining and nullish coalescing, asynchronous functions with async/await, and new Promise methods like Promise.allSettled. It also covers trailing commas, symbols, and other language features.

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const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c toString().padStart(width) : cell.padEnd(width); }).join(''))).join }; const proportion = (max, val) => Math.round(val * 100 / max); co calcProportion = table => { table.sort((row1, row2) => row2[DENSITY row1[DENSITY_COL]); const maxDensity = table[0][DENSITY_COL]; table forEach(row => { row.push(proportion(maxDensity, row[DENSITY_COL])) return table; }; const getDataset = file => { const lines = fs.read FileSync(file, 'utf8').toString().split('n'); lines.shift(); lines return lines.map(line => line.split(',')); }; const main = compose (getDataset, calcProportion, renderTable); const fs = require('fs' compose = (...funcs) => x => funcs.reduce((x, fn) => fn(x), x); con DENSITY_COL = 3; const renderTable = table => { const cellWidth = [ 8, 8, 18, 6]; return table.map(row => (row.map((cell, i) => { const = cellWidth[i]; return i ? cell.toString().padStart(width) : cell.p (width); }).join(''))).join('n'); }; const proportion = (max, val) Новое в JavaScript ES.Next, ECMAScript 2020 Тимур Шемсединов github.com/HowProgrammingWorks Chief Software Architect at Metarhia Lecturer at Kiev Polytechnic Institute github.com/tshemsedinov
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c ECMA Script versions ES1 Jun 1997 ES6 ES2015 ES2 Jun 1998 ES7 ES2016 ES3 Dec 1999 ES8 ES2017 ES5 Dec 2009 ES9 ES2018 ES5.1 Jun 2011 ES10 ES2019 ES11 ES2020 ES.Next
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Links ES2020 https://tc39.es/ecma262/ Node Green https://node.green/ Proposals https://github.com/tc39/proposals Can I use https://caniuse.com/
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Array Array.prototype.includes(value[, fromIndex]) Array.prototype.flat([depth]) Array.prototype.flatMap(callback[, thisArg]) Array.prototype.sort([compareFunction]) QuickSort to TimSort
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Object Object.values(object) Object.keys(object) Object.entries(object) Object.fromEntries(object)
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c String String.prototype.padStart(targetLength [, padString]) String.prototype.padEnd(targetLength [, padString]) String.prototype.trimStart() String.prototype.trimEnd()
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Operators Rest const f = (a, b, ...array) => {}; const g = ({ a, b, ...array }) => {}; const { name, ...rest } = obj; Spread f(a, b, ...array); const obj2 = { name, ...obj1 }; const clone = { ...obj };
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Operators Exponentiation Math.pow(x, y) x ** y x **= y x = x ** y Optional chaining const spqr = { emperor: { name: 'Marcus' } }; console.log(spqr.emperor?.name); console.log(spqr.president?.name);
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Asynchronous function: async/await const fn = async (a, b, c) => { // do something await callSomething(); // do something return aValue; };
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Trailing commas const fn = (arg1, arg2, arg3,) => { console.log({ arg1, arg2, arg3, }); }; fn(...['val1', 'val2', ], 'val3',);
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Asynchronous iterable contract Symbol.iterator iterable[Symbol.iterator]() Symbol.asyncIterator asyncIterable[Symbol.asyncIterator]()
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Try...catch try { throw new Error('message'); } catch { console.log('no arguments catched'); }
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Function ((a, b) => { const c = a + b; // hello there return c; }).toString() "(a, b) => { const c = a + b; // hello there return c; }"
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Symbol const sym = Symbol('description'); console.log(sym); // Symbol(description); console.log(sym.description); // description
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Promise.finally new Promise(executor) .then(onFulfilled[, onRejected]) .catch(onRejected) .finally(onFinally);
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Promise.allSettled const p1 = Promise.resolve('p1'); const p2 = new Promise((resolve, reject) => { setTimeout(resolve, 1000, 'p2'); }); const p3 = new Promise((resolve, reject) => { setTimeout(reject, 100, 'p3'); }); Promise.all([p1, p2, p3]).then(values => { console.log(values); });
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Promise.allSettled Promise.all([p1, p2, p3]).then(values => { console.log(values); }); node:26549) UnhandledPromiseRejectionWarning: p3 (node:26549) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1) (node:26549) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Promise.allSettled const p1 = Promise.resolve('p1'); const p2 = new Promise((resolve, reject) => { setTimeout(resolve, 1000, 'p2'); }); const p3 = new Promise((resolve, reject) => { setTimeout(reject, 100, 'p3'); }); Promise.allSettled([p1, p2, p3]).then(values => { console.log(values); });
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Promise.allSettled Promise.allSettled([p1, p2, p3]).then(values => { console.log(values); }); [ { status: 'fulfilled', value: 'p1' }, { status: 'fulfilled', value: 'p2' }, { status: 'rejected', reason: 'p3' } ]
const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c More features Atomics SheredArrayBuffer Set, Map, WeakSet, WeakMap globalThis Private fields Static fields

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Новое в JavaScript: ES.Next, ECMAScript 2020, ES11, ES10, ES9, ES8, ES7, ES6, ES2020, ES2019

  • 1. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c toString().padStart(width) : cell.padEnd(width); }).join(''))).join }; const proportion = (max, val) => Math.round(val * 100 / max); co calcProportion = table => { table.sort((row1, row2) => row2[DENSITY row1[DENSITY_COL]); const maxDensity = table[0][DENSITY_COL]; table forEach(row => { row.push(proportion(maxDensity, row[DENSITY_COL])) return table; }; const getDataset = file => { const lines = fs.read FileSync(file, 'utf8').toString().split('n'); lines.shift(); lines return lines.map(line => line.split(',')); }; const main = compose (getDataset, calcProportion, renderTable); const fs = require('fs' compose = (...funcs) => x => funcs.reduce((x, fn) => fn(x), x); con DENSITY_COL = 3; const renderTable = table => { const cellWidth = [ 8, 8, 18, 6]; return table.map(row => (row.map((cell, i) => { const = cellWidth[i]; return i ? cell.toString().padStart(width) : cell.p (width); }).join(''))).join('n'); }; const proportion = (max, val) Новое в JavaScript ES.Next, ECMAScript 2020 Тимур Шемсединов github.com/HowProgrammingWorks Chief Software Architect at Metarhia Lecturer at Kiev Polytechnic Institute github.com/tshemsedinov
  • 2. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c ECMA Script versions ES1 Jun 1997 ES6 ES2015 ES2 Jun 1998 ES7 ES2016 ES3 Dec 1999 ES8 ES2017 ES5 Dec 2009 ES9 ES2018 ES5.1 Jun 2011 ES10 ES2019 ES11 ES2020 ES.Next
  • 3. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Links ES2020 https://tc39.es/ecma262/ Node Green https://node.green/ Proposals https://github.com/tc39/proposals Can I use https://caniuse.com/
  • 4. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Array Array.prototype.includes(value[, fromIndex]) Array.prototype.flat([depth]) Array.prototype.flatMap(callback[, thisArg]) Array.prototype.sort([compareFunction]) QuickSort to TimSort
  • 5. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Object Object.values(object) Object.keys(object) Object.entries(object) Object.fromEntries(object)
  • 6. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c String String.prototype.padStart(targetLength [, padString]) String.prototype.padEnd(targetLength [, padString]) String.prototype.trimStart() String.prototype.trimEnd()
  • 7. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Operators Rest const f = (a, b, ...array) => {}; const g = ({ a, b, ...array }) => {}; const { name, ...rest } = obj; Spread f(a, b, ...array); const obj2 = { name, ...obj1 }; const clone = { ...obj };
  • 8. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Operators Exponentiation Math.pow(x, y) x ** y x **= y x = x ** y Optional chaining const spqr = { emperor: { name: 'Marcus' } }; console.log(spqr.emperor?.name); console.log(spqr.president?.name);
  • 9. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Asynchronous function: async/await const fn = async (a, b, c) => { // do something await callSomething(); // do something return aValue; };
  • 10. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Trailing commas const fn = (arg1, arg2, arg3,) => { console.log({ arg1, arg2, arg3, }); }; fn(...['val1', 'val2', ], 'val3',);
  • 11. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Asynchronous iterable contract Symbol.iterator iterable[Symbol.iterator]() Symbol.asyncIterator asyncIterable[Symbol.asyncIterator]()
  • 12. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Try...catch try { throw new Error('message'); } catch { console.log('no arguments catched'); }
  • 13. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Function ((a, b) => { const c = a + b; // hello there return c; }).toString() "(a, b) => { const c = a + b; // hello there return c; }"
  • 14. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Symbol const sym = Symbol('description'); console.log(sym); // Symbol(description); console.log(sym.description); // description
  • 15. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Promise.finally new Promise(executor) .then(onFulfilled[, onRejected]) .catch(onRejected) .finally(onFinally);
  • 16. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Promise.allSettled const p1 = Promise.resolve('p1'); const p2 = new Promise((resolve, reject) => { setTimeout(resolve, 1000, 'p2'); }); const p3 = new Promise((resolve, reject) => { setTimeout(reject, 100, 'p3'); }); Promise.all([p1, p2, p3]).then(values => { console.log(values); });
  • 17. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Promise.allSettled Promise.all([p1, p2, p3]).then(values => { console.log(values); }); node:26549) UnhandledPromiseRejectionWarning: p3 (node:26549) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1) (node:26549) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
  • 18. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Promise.allSettled const p1 = Promise.resolve('p1'); const p2 = new Promise((resolve, reject) => { setTimeout(resolve, 1000, 'p2'); }); const p3 = new Promise((resolve, reject) => { setTimeout(reject, 100, 'p3'); }); Promise.allSettled([p1, p2, p3]).then(values => { console.log(values); });
  • 19. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c Promise.allSettled Promise.allSettled([p1, p2, p3]).then(values => { console.log(values); }); [ { status: 'fulfilled', value: 'p1' }, { status: 'fulfilled', value: 'p2' }, { status: 'rejected', reason: 'p3' } ]
  • 20. const fs = require('fs'); const compose = (...funcs) => x => funcs. reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma => (row.map((cell, i) => { const width = cellWidth[i]; return i ? c More features Atomics SheredArrayBuffer Set, Map, WeakSet, WeakMap globalThis Private fields Static fields