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.

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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 }) { ; }   }}

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

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