ECMAScript 2023 & Temporal All In One

ES2023 / ES14

`stage 3` Temporal

https://github.com/tc39/proposal-temporal
https://github.com/tc39/proposals#stage-3
~~https://github.com/tc39/proposals/blob/main/README.md#stage-3~~

✅
https://github.com/tc39/proposals/blob/main/finished-proposals.md
⏳
https://github.com/tc39/proposals/blob/main/stage-1-proposals.md
https://github.com/tc39/proposals/blob/main/stage-0-proposals.md
❌
https://github.com/tc39/proposals/blob/main/inactive-proposals.md

change Array by `copy` new array

Array.toReversed()

const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9];
const reversed = numbers.toReversed();

console.log("reversed =", reversed);
// reversed = [9, 8, 7, 6, 5, 4, 3, 2, 1]
console.log("original =", numbers);
// original = [1, 2, 3, 4, 5, 6, 7, 8, 9]

Array.toSorted()

const numbers = [9, 5, 4, 3, 2, 8, 7, 6, 1];
const sortedArr = numbers.toSorted();

console.log("sorted =", sortedArr);
// sorted = [1, 2, 3, 4, 5, 6, 7, 8, 9]
console.log("original = ", numbers);
// original = [9, 5, 4, 3, 2, 8, 7, 6, 1];

Array.with()

const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9]
const replaceWith = numbers.with(1, `✅`);

console.log("with =", replaceWith);
// with = [1, `✅`, 3, 4, 5, 6, 7, 8, 9]
console.log("original =", numbers);
// original = [1, 2, 3, 4, 5, 6, 7, 8, 9]

Array.toSpliced()

const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9]
const splicedArr = numbers.toSpliced(0, 3);

console.log("toSpliced  =", splicedArr);
// toSpliced  = [4, 5, 6, 7, 8, 9]
console.log("original", numbers);
// original = [1, 2, 3, 4, 5, 6, 7, 8, 9]

Array.findLast()

const arr = [{v: 3, i: 1}, {v: 2, i: 2}, {v: 3, i: 3}, {v: 2, i: 4}];
const lastV2 = arr.findLast(obj => obj.v === 2);

console.log(`lastV2 =`, lastV2);
// lastV2 = {v: 2, i: 4}

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findLast

If you extend the built in Array object and use map, flatMap, filter, or concat on an instance, it will return a new instance of the same type.
If you extend an Array and use toSorted, toReversed, toSpliced, or with the result will be a plain Array again.

class customArray extends Array {
  //
}
const languages = new customArray("JavaScript", "TypeScript", "CoffeeScript");
const upcase = languages.map(language => language.toUpperCase());

languages;
// customArray(3) ['JavaScript', 'TypeScript', 'CoffeeScript']
upcase;
// customArray(3) ['JAVASCRIPT', 'TYPESCRIPT', 'COFFEESCRIPT']
console.log(upcase instanceof customArray);
// true

// copy ✅
const reversed = languages.toReversed();
reversed;
// (3) ['CoffeeScript', 'TypeScript', 'JavaScript']
console.log(reversed instanceof customArray);
// false

// recovery ✅
const recovery = customArray.from(reversed);
recovery;
// customArray(3) ['CoffeeScript', 'TypeScript', 'JavaScript']
console.log(recovery instanceof customArray);
// true

Hashbang / Shebang `#!`

#!/usr/bin/env bash

#!/usr/bin/env node
// in the Script Goal
'use strict';
console.log(2*3);

#!/usr/bin/env node
// in the Module Goal
export {};
console.log(2*2);

ES-Next `Temporal` ⚠️

ES2023 / ES14

This Stage 3 proposal is experimental.

Date has been a long-standing pain point in ECMAScript.
This is a proposal for Temporal, a global Object that acts as a top-level namespace (like Math), that brings a modern date/time API to the ECMAScript language.
For a detailed look at some of the problems with Date, and the motivations for Temporal, see: Fixing JavaScript Date.

Temporal fixes these problems by:

Providing easy-to-use APIs for date and time computations
First-class support for all time zones, including DST-safe arithmetic
Dealing only with objects representing fixed dates and times
Parsing a strictly specified string format
Supporting non-Gregorian calendars
Temporal provides separate ECMAScript classes for date-only, time-only, and other scoped use cases.
This makes code more readable and prevents bugs caused by incorrectly assuming 0, UTC, or the local time zone for values that are actually unknown.

https://tc39.es/proposal-temporal/docs/

https://github.com/tc39/proposal-temporal

https://caniuse.com/?search=Temporal

demos

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ECMA-262

ECMA-262 5.1 edition, June 2011 ES5
ECMA-262, 6th edition, June 2015 ES6
ECMA-262, 7th edition, June 2016
ECMA-262, 8th edition, June 2017
ECMA-262, 9th edition, June 2018
ECMA-262, 10th edition, June 2019
ECMA-262, 11th edition, June 2020
ECMA-262, 12th edition, June 2021
ECMA-262, 13th edition, June 2022 ES2022

ECMA-262, 14th edition, June 2023 ??? ES2023 / ES14

https://www.ecma-international.org/publications-and-standards/standards/ecma-262/

# ES + year => ES + (year+1)
ES2015 => ES6
ES2016 => ES7
ES2017 => ES8
ES2018 => ES9
ES2019 => ES10
ES2020 => ES11
ES2021 => ES12
ES2022 => ES13
ES2023 => ES14
...
ES2024 => ES15
ES2025 => ES16
...
ES2030 => ES31
...
ES2050 => ES51