May 13th, 2020 × #ES2019#ES2020#JavaScript

What's New in Javascript

Covers new JavaScript features coming in ES2019 and ES2020 including flat map, knowledge coalescing, global this, optional chaining and more.


In this episode of Syntax, Scott and Wes talk about what is new in Javascript — a whole bunch of new stuff that you can use now and in the next sixth months or so.

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Show Notes


04:03 - Array.flatMap() 05:30 - Array.flat() 07:37 - Array.fromEntries() 09:50 - String.trimStart() and String.trimEnd() 11:23 - Function.toString() 11:57 - Object Key Order

  1. Integer keys in ascending order (and strings like "1" that parse as ints)
  2. String keys, in insertion order (ES2015 guarantees this and all browsers comply)
  3. Symbol names, in insertion order (ES2015 guarantees this and all browsers comply)


14:50 - Big int 18:09 - Nullish coalescing 20:57 - Optional Chaining 24:55 - promise.allSettled 25:33 - Dynamic import 27:14 - string.matchAll(regex) and string.replaceAll 29:30 - globalThis 30:44 - Module Namespace Exports 33:11 - Navigator.share() API 36:34 - Async Hooks 37:39 - Pipline Operator 39:59 - Top Level Await


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