Hasty Treat - Seven Interesting JavaScript Proposals - Async Do, JSON Modules, Immutable Array Methods, and More!

   Promise.all([   async do {     let result = await fetch('thing A');     await result.json();   },   async do {     let result = await fetch('thing B');     await result.json();   }, ]).then(([a, b]) => console.log([a, b]));   

   {props => match (props) {     when ({ loading }) {; }     when ({ error }) {; }     when ({ data }) {; }   }}   

In this Hasty Treat, Scott and Wes talk about seven new JavaScript proposals — what they do, where they’re at, and how you might use them. Deque - Sponsor Deque’s axe DevTools makes accessibility testing easy and doesn’t require special expertise. Find and fix issues while you code. Get started with a free trial of axe DevTools Pro at deque.com/syntax. No credit card needed. LogRocket - Sponsor LogRocket lets you replay what users do on your site, helping you reproduce bugs and fix issues faster. It’s an exception tracker, a session re-player and a performance monitor. Get 14 days free at logrocket.com/syntax. Show Notes 03:32 - Seven new JavaScript proposals https://github.com/tc39/proposals 06:25 - JSON Modules https://github.com/tc39/proposal-json-modules Builds on the import assertions No named exports Not executed, to avoid security issues Not in Node yet 09:55 - Array Find From Last https://github.com/tc39/proposal-array-find-from-last The problem: you need to group together async code.The only way to do that right now is to wrap it in a function. 11:40 - Async Do https://github.com/tc39/proposal-async-do-expressions Async do will allow you to group together a block of code and mark it as async. No need for an iife Downside to this is that it’s a code block, so if you need to return any values, you’ll need to jump that up a scope level. Promise.all([ async do { let result = await fetch('thing A'); await result.json(); }, async do { let result = await fetch('thing B'); await result.json(); }, ]).then(([a, b]) => console.log([a, b])); 14:33 - Change Array By Copy https://github.com/tc39/proposal-change-array-by-copy Like old array methods, but returns a new array rather than mutating 17:48 - Temporal https://github.com/tc39/proposal-temporal Stage 3, looking good! Amazing, large, very good Date API Syntax 295: Hasty Treat — Temporal Date Objects in JavaScript 18:35 - As Patterns https://github.com/zkat/proposal-as-patterns Scott don’t get it Stage 0 when ([ ‘go’, (‘north’ | ‘east’ | ‘south’ | ‘west’) as dir ]) { … } 20:47 - Pattern Matching https://github.com/tc39/proposal-pattern-matching VERY Rust-like https://doc.rust-lang.org/1.6.0/book/patterns.html Stage 1 {props => match (props) { when ({ loading }) { ; } when ({ error }) { ; } when ({ data }) { ; } }} Tweet us your tasty treats! Scott’s Instagram LevelUpTutorials Instagram Wes’ Instagram Wes’ Twitter Wes’ Facebook Scott’s Twitter Make sure to include @SyntaxFM in your tweets